Method for transmitting uplink signal in a wireless communication system and apparatus for the same

ABSTRACT

Provided are a method of transmitting, by a user equipment, a uplink signal in a wireless communication system. The method includes receiving control information related to a codeword cover used for a multiplexing of a multiple of user equipments from a base station, generating a transmission symbol of a specific length by repeating a data symbol in a specific time unit, generating the uplink signal by applying the codeword cover of the specific length to the generated transmission symbol, and transmitting the generated uplink signal to the base station through a single tone.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119(e), this application claims the benefit ofU.S. Provisional Patent Application No. 62/264,855, filed on Dec. 8,2015, the contents of which are hereby incorporated by reference hereinin their entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a wireless communication system, moreparticularly, to a method of transmitting an UL single in a wirelesscommunication system and apparatus for supporting the same.

Related Art

Mobile communication systems have been developed to provide voiceservices while ensuring the activity of a user. However, the mobilecommunication systems have been expanded to their regions up to dataservices as well as voice. Today, the shortage of resources is causeddue to an explosive increase of traffic, and more advanced mobilecommunication systems are required due to user's need for higher speedservices.

Requirements for a next-generation mobile communication system basicallyinclude the acceptance of explosive data traffic, a significant increaseof a transfer rate per user, the acceptance of the number ofsignificantly increased connection devices, very low end-to-end latency,and high energy efficiency. To this end, research is carried out onvarious technologies, such as dual connectivity, massive Multiple InputMultiple Output (MIMO), in-band full duplex, Non-Orthogonal MultipleAccess (NOMA), the support of a super wideband, and device networking.

SUMMARY OF THE INVENTION

The present invention provides a method of supporting a multiplexingbetween user equipments (UEs) through an orthogonal codeword cover usinga DFT matrix in NB-IoT system.

The present invention also provides a method of allocating a codewordcover to UEs in consideration of a coverage class in order to avoid aninter-cell interference in NB-IoT system.

The present invention also provides a method of supporting amultiplexing between UEs by using a frequency hopping method.

In an aspect, a method of transmitting, by a user equipment, a uplinksignal in a wireless communication system is provided. The methodincludes receiving control information related to a codeword cover usedfor a multiplexing of a multiple of user equipments from a base station,generating a transmission symbol of a specific length by repeating adata symbol in a specific time unit, generating the uplink signal byapplying the codeword cover of the specific length to the generatedtransmission symbol, and transmitting the generated uplink signal to thebase station through a single tone.

The specific time unit may be a symbol unit, a symbol group unit, a slotunit, a subframe unit, a subframe group unit, or a wireless frame unit.

The codeword cover of the specific length may be an orthogonal codewordcover which is generated using a DFT (discrete Fourier transform)matrix.

The codeword cover of the specific length may be an orthogonal codewordcover corresponding to a specific row vector of the DFT matrix.

The row vector of the DFT matrix may have indexes of from 0 to {(valueof a specific length)−1}, and the specific row vector may be a rowvector corresponding to an index close to the value of the specificlength or 0.

The codeword cover may have a mapping relation with a coverage class.

The coverage class may be determined using at least one of a distancebetween the user equipment and the base station, a size of a receivingpower in the base station, and a size of an interference influencing anadjacent cell.

The control information may further include at least one of frequencyhopping information indicating a frequency hopping pattern related totransmission of the uplink signal or information indicating whether thefrequency hopping is used.

The frequency hopping pattern may be configured differently per cell.

The control information may be received from the base station throughRRC (radio resource control) signaling or DCI (downlink controlinformation).

In another aspect, a user equipment for transmitting an uplink signal ina wireless communication is provided. The user equipment includes aradio frequency (RF) unit for transmitting/receiving a wireless signaland a processor functionally connected to the RF unit, wherein theprocessor is controlled to control information related to a codewordcover used for a multiplexing of a multiple of user equipments from abase station, generate a transmission symbol of a specific length byrepeating a data symbol in a specific time unit, generate the uplinksignal by applying the codeword cover of the specific length to thegenerated transmission symbol, and transmit the generated uplink signalto the base station through a single tone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the structure of a wireless frame in a wirelesscommunication system to which the present invention is applicable.

FIG. 2 illustrates a resource grid for one DL slot in a wirelesscommunication system to which the present invention is applicable.

FIG. 3 illustrates the structure of a DL subframe in a wirelesscommunication system to which the present invention is applicable.

FIG. 4 illustrates the structure of an UL subframe in a wirelesscommunication system to which the present invention is applicable.

FIG. 5 illustrates an example of a form in which PUCCH formats aremapped to a PUCCH area of an UL physical resource block in a wirelesscommunication system to which the present invention is applicable.

FIG. 6 illustrates the structure of CQI channel in the case of a generalCP in a wireless communication system to which the present invention isapplicable.

FIG. 7 illustrates the structure of ACK/NACK channel in the case of ageneral CP in a wireless communication system to which the presentinvention is applicable.

FIG. 8 illustrates an example of generating 5 SC-FDMA symbols during oneslot and generating the generated 5 SC-FDMA symbols in a wirelesscommunication system to which the present invention is applicable.

FIG. 9 illustrates an example of a component carrier and a carrieraggregation in a wireless communication system to which the presentinvention is applicable.

FIG. 10 illustrates an example of a subframe structure according to across carrier scheduling in a wireless communication system to which thepresent invention is applicable.

FIG. 11 illustrates an example of a transmission channel processing ofan UL-SCH in a wireless communication system to which the presentinvention is applicable.

FIG. 12 illustrates an example of a signal processing process of an ULshared channel which is a transport channel in a wireless communicationsystem to which the present application is applicable.

FIG. 13 illustrates a reference signal pattern which is mapped on a DLresource block pair in a wireless communication system to which thepresent invention is applicable.

FIG. 14 illustrates an UL subframe including a sounding reference signalsymbol in a wireless communication system to which the present inventionis applicable.

FIG. 15 illustrates an example of a multiplexing of legacy PDCCH, PDSCHand EPDCCH.

FIG. 16 illustrates a section of a cell division of a system supportinga carrier aggregation.

FIG. 17 illustrates the structure of a frame used for SS transmission ina system which uses a basic CP (Cyclic Prefix).

FIG. 18 illustrates a frame structure used for SS transmission in asystem which uses an extended CP.

FIG. 19 illustrates two sequences in a logical region being interleavedand mapped in a physical region.

FIG. 20 illustrates a frame structure in which M-PSS and M-SSS aremapped.

FIG. 21 illustrates a method of generating M-PSS according to anembodiment of the present invention.

FIG. 22 illustrates a method of generating M-SSS according to anembodiment of the present invention.

FIG. 23 illustrates an example of a method of implementing M-PSS towhich a method proposed in the present specification is applicable.

FIG. 24 illustrates how UL numerology is stretched in a time domain.

FIG. 25 illustrates an example of time units for the UL of NB-LTE basedon 2.5 kHz subcarrier spacing.

FIG. 26(a) illustrates an in-band system.

FIG. 26(b) illustrates a guard-band system.

FIG. 26(c) illustrates a stand-alone system.

FIG. 27 illustrates an example of an NB-frame structure of 15 kHzsubcarrier spacing to which the method proposed in the presentspecification is applicable.

FIG. 28 illustrates an example of NB-frame structure for 3.75 kHzsubcarrier spacing to which the method proposed in the presentspecification is applicable.

FIG. 29 illustrates an example of NB subframe structure in 3.75 kHzsubcarrier spacing to which the method proposed in the presentspecification is applicable.

FIG. 30 illustrates an example of PUSCH processing in NB-IoT system towhich the method proposed in the present specification is applicable.

FIG. 31 illustrates an example of an LTE turbo encoder used for PUSCH inNB-IoT system to which the method proposed in the present specificationis applicable.

FIG. 32 illustrates an example of a method of applying a codeword coverproposed in the present specification to a repeated symbol of a timedomain.

FIG. 33 illustrates an example of a method of using different orthogonalcodes depending on the coverage class proposed in the presentspecification.

FIG. 34 illustrates an example of a method of multiplexing an UL systemof a user equipment by using a codeword cover and a frequency hoppingpattern which are proposed in the present specification.

FIG. 35 is a flowchart showing an example of a method of multiplexing anUL signal between user equipments, which is proposed in the presentspecification.

FIG. 36 illustrates an example of an internal block diagram of awireless communication device to which the methods proposed in thepresent specification are applicable.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Adetailed description to be disclosed hereinbelow together with theaccompanying drawing is to describe embodiments of the present inventionand not to describe a unique embodiment for carrying out the presentinvention. The detailed description below includes details in order toprovide a complete understanding. However, those skilled in the art knowthat the present invention can be carried out without the details.

In some cases, in order to prevent a concept of the present inventionfrom being ambiguous, known structures and devices may be omitted or maybe illustrated in a block diagram format based on core function of eachstructure and device.

In the specification, a base station means a terminal node of a networkdirectly performing communication with a terminal. In the presentdocument, specific operations described to be performed by the basestation may be performed by an upper node of the base station in somecases. That is, it is apparent that in the network constituted bymultiple network nodes including the base station, various operationsperformed for communication with the terminal may be performed by thebase station or other network nodes other than the base station. A basestation (BS) may be generally substituted with terms such as a fixedstation, Node B, evolved-NodeB (eNB), a base transceiver system (BTS),an access point (AP), and the like. Further, a ‘terminal’ may be fixedor movable and be substituted with terms such as user equipment (UE), amobile station (MS), a user terminal (UT), a mobile subscriber station(MSS), a subscriber station (SS), an dvanced mobile station (AMS), awireless terminal (WT), a Machine-Type Communication (MTC) device, aMachine-to-Machine (M2M) device, a Device-to-Device (D2D) device, andthe like.

Hereinafter, a downlink means communication from the base station to theterminal and an uplink means communication from the terminal to the basestation. In the downlink, a transmitter may be a part of the basestation and a receiver may be a part of the terminal. In the uplink, thetransmitter may be a part of the terminal and the receiver may be a partof the base station.

Specific terms used in the following description are provided to helpappreciating the present invention and the use of the specific terms maybe modified into other forms within the scope without departing from thetechnical spirit of the present invention.

The following technology may be used in various wireless access systems,such as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), single carrier-FDMA(SC-FDMA), non-orthogonal multiple access (NOMA), and the like. The CDMAmay be implemented by radio technology universal terrestrial radioaccess (UTRA) or CDMA2000. The TDMA may be implemented by radiotechnology such as Global System for Mobile communications (GSM)/GeneralPacket Radio Service(GPRS)/Enhanced Data Rates for GSM Evolution (EDGE).The OFDMA may be implemented as radio technology such as IEEE802.11(Wi-Fi), IEEE 802.16(WiMAX), IEEE 802-20, E-UTRA(Evolved UTRA),and the like. The UTRA is a part of a universal mobile telecommunicationsystem (UMTS). 3rd generation partnership project (3GPP) long termevolution (LTE) as a part of an evolved UMTS (E-UMTS) using evolved-UMTSterrestrial radio access (E-UTRA) adopts the OFDMA in a downlink and theSC-FDMA in an uplink. LTE-advanced (A) is an evolution of the 3GPP LTE.

The embodiments of the present invention may be based on standarddocuments disclosed in at least one of IEEE 802, 3GPP, and 3GPP2 whichare the wireless access systems. That is, steps or parts which are notdescribed to definitely show the technical spirit of the presentinvention among the embodiments of the present invention may be based onthe documents. Further, all terms disclosed in the document may bedescribed by the standard document.

3GPP LTE/LTE-A is primarily described for clear description, buttechnical features of the present invention are not limited thereto.

General System

FIG. 1 illustrates a structure a radio frame in a wireless communicationsystem to which the present invention can be applied.

In 3GPP LTE/LTE-A, radio frame structure type 1 may be applied tofrequency division duplex (FDD) and radio frame structure type 2 may beapplied to time division duplex (TDD) are supported.

FIG. 1(a) exemplifies radio frame structure type 1. The radio frame isconstituted by 10 subframes. One subframe is constituted by 2 slots in atime domain. A time required to transmit one subframe is referred to asa transmissions time interval (TTI). For example, the length of onesubframe may be 1 ms and the length of one slot may be 0.5 ms.

One slot includes a plurality of orthogonal frequency divisionmultiplexing (OFDM) symbols in the time domain and includes multipleresource blocks (RBs) in a frequency domain. In 3GPP LTE, since OFDMA isused in downlink, the OFDM symbol is used to express one symbol period.The OFDM symbol may be one SC-FDMA symbol or symbol period. The resourceblock is a resource allocation wise and includes a plurality ofconsecutive subcarriers in one slot.

FIG. 1(b) illustrates frame structure type 2. Radio frame type 2 isconstituted by 2 half frames, each half frame is constituted by 5subframes, a downlink pilot time slot (DwPTS), a guard period (GP), andan uplink pilot time slot (UpPTS), and one subframe among them isconstituted by 2 slots. The DwPTS is used for initial cell discovery,synchronization, or channel estimation in a terminal. The UpPTS is usedfor channel estimation in a base station and to match uplinktransmission synchronization of the terminal. The guard period is aperiod for removing interference which occurs in uplink due tomulti-path delay of a downlink signal between the uplink and thedownlink.

In frame structure type 2 of a TDD system, an uplink-downlinkconfiguration is a rule indicating whether the uplink and the downlinkare allocated (alternatively, reserved) with respect to all subframes.Table 1 shows he uplink-downlink configuration.

TABLE 1 Downlink- to-Uplink Uplink Switch- Downlink point Subframenumber configuration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U DS U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  DS U U U D D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D D DD D 6 5 ms D S U U U D S U U D

Referring to Table 1, for each sub frame of the radio frame, ‘D’represents a subframe for downlink transmission, ‘U’ represents asubframe for uplink transmission, and ‘S’ represents a special subframeconstituted by three fields such as the DwPTS, the GP, and the UpPTS.The uplink-downlink configuration may be divided into 7 configurationsand the positions and/or the numbers of the downlink subframe, thespecial subframe, and the uplink subframe may vary for eachconfiguration.

A time when the downlink is switched to the uplink or a time when theuplink is switched to the downlink is referred to as a switching point.Switch-point periodicity means a period in which an aspect of the uplinksubframe and the downlink subframe are switched is similarly repeatedand both 5 ms or 10 ms are supported. When the period of thedownlink-uplink switching point is 5 ms, the special subframe S ispresent for each half-frame and when the period of the downlink-uplinkswitching point is 5 ms, the special subframe S is present only in afirst half-frame.

In all configurations, subframes #0 and #5 and the DwPTS are intervalsonly the downlink transmission. The UpPTS and a subframe justsubsequently to the subframe are continuously intervals for the uplinktransmission.

The uplink-downlink configuration may be known by both the base stationand the terminal as system information. The base station transmits onlyan index of configuration information whenever the uplink-downlinkconfiguration information is changed to announce a change of anuplink-downlink allocation state of the radio frame to the terminal.Further, the configuration information as a kind of downlink controlinformation may be transmitted through a physical downlink controlchannel (PDCCH) similarly to other scheduling information and may becommonly transmitted to all terminals in a cell through a broadcastchannel as broadcasting information.

The structure of the radio frame is just one example and the numbersubcarriers included in the radio frame or the number of slots includedin the subframe and the number of OFDM symbols included in the slot maybe variously changed.

FIG. 2 is a diagram illustrating a resource grid for one downlink slotin the wireless communication system to which the present invention canbe applied.

Referring to FIG. 2, one downlink slot includes the plurality of OFDMsymbols in the time domain. Herein, it is exemplarily described that onedownlink slot includes 7 OFDM symbols and one resource block includes 12subcarriers in the frequency domain, but the present invention is notlimited thereto.

Each element on the resource grid is referred to as a resource elementand one resource block includes 12×7 resource elements. The number ofresource blocks included in the downlink slot, NDL is subordinated to adownlink transmission bandwidth.

A structure of the uplink slot may be the same as that of the downlinkslot.

FIG. 3 illustrates a structure of a downlink subframe in the wirelesscommunication system to which the present invention can be applied.

Referring to FIG. 3, a maximum of three fore OFDM symbols in the firstslot of the sub frame is a control region to which control channels areallocated and residual OFDM symbols is a data region to which a physicaldownlink shared channel (PDSCH) is allocated. Examples of the downlinkcontrol channel used in the 3GPP LTE include a Physical Control FormatIndicator Channel (PCFICH), a Physical Downlink Control Channel (PDCCH),a Physical Hybrid-ARQ Indicator Channel (PHICH), and the like.

The PFCICH is transmitted in the first OFDM symbol of the subframe andtransports information on the number (that is, the size of the controlregion) of OFDM symbols used for transmitting the control channels inthe subframe. The PHICH which is a response channel to the uplinktransports an Acknowledgement (ACK)/Not-Acknowledgement (NACK) signalfor a hybrid automatic repeat request (HARQ). Control informationtransmitted through a PDCCH is referred to as downlink controlinformation (DCI). The downlink control information includes uplinkresource allocation information, downlink resource allocationinformation, or an uplink transmission (Tx) power control command for apredetermined terminal group.

The PDCCH may transport A resource allocation and transmission format(also referred to as a downlink grant) of a downlink shared channel(DL-SCH), resource allocation information (also referred to as an uplinkgrant) of an uplink shared channel (UL-SCH), paging information in apaging channel (PCH), system information in the DL-SCH, resourceallocation for an upper-layer control message such as a random accessresponse transmitted in the PDSCH, an aggregate of transmission powercontrol commands for individual terminals in the predetermined terminalgroup, a voice over IP (VoIP). A plurality of PDCCHs may be transmittedin the control region and the terminal may monitor the plurality ofPDCCHs. The PDCCH is constituted by one or an aggregate of a pluralityof continuous control channel elements (CCEs). The CCE is a logicalallocation wise used to provide a coding rate depending on a state of aradio channel to the PDCCH. The CCEs correspond to a plurality ofresource element groups. A format of the PDCCH and a bit number ofusable PDCCH are determined according to an association between thenumber of CCEs and the coding rate provided by the CCEs.

The base station determines the PDCCH format according to the DCI to betransmitted and attaches the control information to a cyclic redundancycheck (CRC) to the control information. The CRC is masked with a uniqueidentifier (referred to as a radio network temporary identifier (RNTI))according to an owner or a purpose of the PDCCH. In the case of a PDCCHfor a specific terminal, the unique identifier of the terminal, forexample, a cell-RNTI (C-RNTI) may be masked with the CRC. Alternatively,in the case of a PDCCH for the paging message, a paging indicationidentifier, for example, the CRC may be masked with a paging-RNTI(P-RNTI). In the case of a PDCCH for the system information, in moredetail, a system information block (SIB), the CRC may be masked with asystem information identifier, that is, a system information (SI)-RNTI.The CRC may be masked with a random access (RA)-RNTI in order toindicate the random access response which is a response to transmissionof a random access preamble.

FIG. 4 illustrates a structure of an uplink subframe in the wirelesscommunication system to which the present invention can be applied.

Referring to FIG. 4, the uplink subframe may be divided into the controlregion and the data region in a frequency domain. A physical uplinkcontrol channel (PUCCH) transporting uplink control information isallocated to the control region. A physical uplink shared channel(PUSCH) transporting user data is allocated to the data region. Oneterminal does not simultaneously transmit the PUCCH and the PUSCH inorder to maintain a single carrier characteristic.

A resource block (RB) pair in the subframe are allocated to the PUCCHfor one terminal. RBs included in the RB pair occupy differentsubcarriers in two slots, respectively. The RB pair allocated to thePUCCH frequency-hops in a slot boundary.

Physical Uplink Control Channel (PUCCH)

The uplink control information (UCI) transmitted through the PUCCH mayinclude a scheduling request (SR), HARQ ACK/NACK information, anddownlink channel measurement information.

The HARQ ACK/NACK information may be generated according to a downlinkdata packet on the PDSCH is successfully decoded. In the existingwireless communication system, 1 bit is transmitted as ACK/NACKinformation with respect to downlink single codeword transmission and 2bits are transmitted as the ACK/NACK information with respect todownlink 2-codeword transmission.

The channel measurement information which designates feedbackinformation associated with a multiple input multiple output (MIMO)technique may include a channel quality indicator (CQI), a precodingmatrix index (PMI), and a rank indicator (RI). The channel measurementinformation may also be collectively expressed as the CQI.

20 bits may be used per subframe for transmitting the CQI.

The PUCCH may be modulated by using binary phase shift keying (BPSK) andquadrature phase shift keying (QPSK) techniques. Control information ofa plurality of terminals may be transmitted through the PUCCH and whencode division multiplexing (CDM) is performed to distinguish signals ofthe respective terminals, a constant amplitude zero autocorrelation(CAZAC) sequence having a length of 12 is primary used. Since the CAZACsequence has a characteristic to maintain a predetermined amplitude inthe time domain and the frequency domain, the CAZAC sequence has aproperty suitable for increasing coverage by decreasing apeak-to-average power ratio (PAPR) or cubic metric (CM) of the terminal.Further, the ACK/NACK information for downlink data transmissionperformed through the PUCCH is covered by using an orthogonal sequenceor an orthogonal cover (OC).

Further, the control information transmitted on the PUCCH may bedistinguished by using a cyclically shifted sequence having differentcyclic shift (CS) values. The cyclically shifted sequence may begenerated by cyclically shifting a base sequence by a specific cyclicshift (CS) amount. The specific CS amount is indicated by the cyclicshift (CS) index. The number of usable cyclic shifts may vary dependingon delay spread of the channel. Various types of sequences may be usedas the base sequence the CAZAC sequence is one example of thecorresponding sequence.

Further, the amount of control information which the terminal maytransmit in one subframe may be determined according to the number (thatis, SC-FDMA symbols other an SC-FDMA symbol used for transmitting areference signal (RS) for coherent detection of the PUCCH) of SC-FDMAsymbols which are usable for transmitting the control information.

In the 3GPP LTE system, the PUCCH is defined as a total of 7 differentformats according to the transmitted control information, a modulationtechnique, the amount of control information, and the like and anattribute of the uplink control information (UCI) transmitted accordingto each PUCCH format may be summarized as shown in Table 2 given below.

TABLE 2 PUCCH Format Uplink Control Information(UCI) Format 1 SchedulingRequest(SR)(unmodulated waveform) Format 1a 1-bit HARQ ACK/NACKwith/without SR Format 1b 2-bit HARQ ACK/NACK with/without SR Format 2CQI (20 coded bits) Format 2 CQI and 1- or 2-bit HARQ ACK/NACK (20 bits)for extended CP only Format 2a CQI and 1-bit HARQ ACK/NACK (20 + 1 codedbits) Format 2b CQI and 2-bit HARQ ACK/NACK (20 + 2 coded bits)

PUCCH format 1 is used for transmitting only the SR. A waveform which isnot modulated is adopted in the case of transmitting only the SR andthis will be described below in detail.

PUCCH format 1a or 1b is used for transmitting the HARQ ACK/NACK. PUCCHformat 1a or 1b may be used when only the HARQ ACK/NACK is transmittedin a predetermined subframe. Alternatively, the HARQ ACK/NACK and the SRmay be transmitted in the same subframe by using PUCCH format 1a or 1b.

PUCCH format 2 is used for transmitting the CQI and PUCCH format 2a or2b is used for transmitting the CQI and the HARQ ACK/NACK.

In the case of an extended CP, PUCCH format 2 may be transmitted fortransmitting the CQI and the HARQ ACK/NACK.

FIG. 5 illustrates one example of a type in which PUCCH formats aremapped to a PUCCH region of an uplink physical resource block in thewireless communication system to which the present invention can beapplied.

In FIG. 5, N_(RB) ^(UL) represents the number of resource blocks in theuplink and 0, 1, . . . , N_(RB) ^(UL)−1 mean numbers of physicalresource blocks. Basically, the PUCCH is mapped to both edges of anuplink frequency block. As illustrated in FIG. 5, PUCCH format 2/2a/2bis mapped to a PUCCH region expressed as m=0, 1 and this may beexpressed in such a manner that PUCCH format 2/2a/2b is mapped toresource blocks positioned at a band edge. Further, both PUCCH format2/2a/2b and PUCCH format 1/1a/1b may be mixedly mapped to a PUCCH regionexpressed as m=2. Next, PUCCH format 1/1a/1b may be mapped to a PUCCHregion expressed as m=3, 4, and 5. The number (N_(RB) ⁽²⁾) of PUCCH RBswhich are usable by PUCCH format 2/2a/2b may be indicated to terminalsin the cell by broadcasting signaling.

PUCCH format 2/2a/2b is described. PUCCH format 2/2a/2b is a controlchannel for transmitting channel measurement feedback (CQI, PMI, andRI).

A reporting period of the channel measurement feedbacks (hereinafter,collectively expressed as CQI information) and a frequency wise(alternatively, a frequency resolution) to be measured may be controlledby the base station. In the time domain, periodic and aperiodic CQIreporting may be supported. PUCCH format 2 may be used for only theperiodic reporting and the PUSCH may be used for aperiodic reporting. Inthe case of the aperiodic reporting, the base station may instruct theterminal to transmit a scheduling resource loaded with individual CQIreporting for the uplink data transmission.

FIG. 6 illustrates a structure of a CQI channel in the case of a generalCP in the wireless communication system to which the present inventioncan be applied.

In SC-FDMA symbols 0 to 6 of one slot, SC-FDMA symbols 1 and 5 (secondand sixth symbols) may be used for transmitting a demodulation referencesignal and the CQI information may be transmitted in the residualSC-FDMA symbols. Meanwhile, in the case of the extended CP, one SC-FDMAsymbol (SC-FDMA symbol 3) is used for transmitting the DMRS.

In PUCCH format 2/2a/2b, modulation by the CAZAC sequence is supportedand the CAZAC sequence having the length of 12 is multiplied by aQPSK-modulated symbol. The cyclic shift (CS) of the sequence is changedbetween the symbol and the slot. The orthogonal covering is used withrespect to the DMRS.

The reference signal (DMRS) is loaded on two SC-FDMA symbols separatedfrom each other by 3 SC-FDMA symbols among 7 SC-FDMA symbols included inone slot and the CQI information is loaded on 5 residual SC-FDMAsymbols. Two RSs are used in one slot in order to support a high-speedterminal. Further, the respective terminals are distinguished by usingthe CS sequence. CQI information symbols are modulated and transferredto all SC-FDMA symbols and the SC-FDMA symbol is constituted by onesequence. That is, the terminal modulates and transmits the CQI to eachsequence.

The number of symbols which may be transmitted to one TTI is 10 andmodulation of the CQI information is determined up to QPSK. When QPSKmapping is used for the SC-FDMA symbol, since a CQI value of 2 bits maybe loaded, a CQI value of 10 bits may be loaded on one slot. Therefore,a CQI value of a maximum of 20 bits may be loaded on one subframe. Afrequency domain spread code is used for spreading the CQI informationin the frequency domain.

The CAZAC sequence (for example, ZC sequence) having the length of 12may be used as the frequency domain spread code. CAZAC sequences havingdifferent CS values may be applied to the respective control channels tobe distinguished from each other. IFFT is performed with respect to theCQI information in which the frequency domain is spread.

12 different terminals may be orthogonally multiplexed on the same PUCCHRB by a cyclic shift having 12 equivalent intervals. In the case of ageneral CP, a DMRS sequence on SC-FDMA symbol 1 and 5 (on SC-FDMA symbol3 in the case of the extended CP) is similar to a CQI signal sequence onthe frequency domain, but the modulation of the CQI information is notadopted.

The terminal may be semi-statically configured by upper-layer signalingso as to periodically report different CQI, PMI, and RI types on PUCCHresources indicated as PUCCH resource indexes (n_(PUCCH)^((1,{tilde over (p)})), n_(PUCCH) ^((2,{tilde over (p)})), andn_(PUCCH) ^((3,{tilde over (p)}))). Herein, the PUCCH resource index(n_(PUCCH) ^((2,{tilde over (p)}))) is information indicating the PUCCHregion used for PUCCH format 2/2a/2b and a CS value to be used.

PUCCH Channel Structure

PUCCH formats 1a and 1b are described.

In PUCCH format 1a and 1b, the CAZAC sequence having the length of 12 ismultiplied by a symbol modulated by using a BPSK or QPSK modulationscheme. For example, a result acquired by multiplying a modulated symbold(0) by a CAZAC sequence r(n) (n=0, 1, 2, . . . , N−1) having a lengthof N becomes y(0), y(1), y(2), . . . , y(N−1). y(0), . . . , y(N−1)symbols may be designated as a block of symbols. The modulated symbol ismultiplied by the CAZAC sequence and thereafter, the block-wise spreadusing the orthogonal sequence is adopted.

A Hadamard sequence having a length of 4 is used with respect to generalACK/NACK information and a discrete Fourier transform (DFT) sequencehaving a length of 3 is used with respect to the ACK/NACK informationand the reference signal.

The Hadamard sequence having the length of 2 is used with respect to thereference signal in the case of the extended CP.

FIG. 7 illustrates a structure of an ACK/NACK channel in the case of ageneral CP in the wireless communication system to which the presentinvention can be applied.

In FIG. 7, a PUCCH channel structure for transmitting the HARQ ACK/NACKwithout the CQI is exemplarily illustrated.

The reference signal (DMRS) is loaded on three consecutive SC-FDMAsymbols in a middle part among 7 SC-FDMA symbols and the ACK/NACK signalis loaded on 4 residual SC-FDMA symbols.

Meanwhile, in the case of the extended CP, the RS may be loaded on twoconsecutive symbols in the middle part. The number of and the positionsof symbols used in the RS may vary depending on the control channel andthe numbers and the positions of symbols used in the ACK/NACK signalassociated with the positions of symbols used in the RS may alsocorrespondingly vary depending on the control channel.

Acknowledgment response information (not scrambled status) of 1 bit and2 bits may be expressed as one HARQ ACK/NACK modulated symbol by usingthe BPSK and QPSK modulation techniques, respectively. A positiveacknowledgement response (ACK) may be encoded as ‘1’ and a negativeacknowledgment response (NACK) may be encoded as ‘0’.

When a control signal is transmitted in an allocated band, 2-dimensional(D) spread is adopted in order to increase a multiplexing capacity. Thatis, frequency domain spread and time domain spread are simultaneouslyadopted in order to increase the number of terminals or control channelswhich may be multiplexed.

A frequency domain sequence is used as the base sequence in order tospread the ACK/NACK signal in the frequency domain. A Zadoff-Chu (ZC)sequence which is one of the CAZAC sequences may be used as thefrequency domain sequence. For example, different CSs are applied to theZC sequence which is the base sequence, and as a result, multiplexingdifferent terminals or different control channels may be applied. Thenumber of CS resources supported in an SC-FDMA symbol for PUCCH RBs forHARQ ACK/NACK transmission is set by a cell-specific upper-layersignaling parameter (Δ_(shift) ^(PUCCH)).

The ACK/NACK signal which is frequency-domain spread is spread in thetime domain by using an orthogonal spreading code. As the orthogonalspreading code, a Walsh-Hadamard sequence or DFT sequence may be used.For example, the ACK/NACK signal may be spread by using an orthogonalsequence (w0, w1, w2, and w3) having the length of 4 with respect to 4symbols. Further, the RS is also spread through an orthogonal sequencehaving the length of 3 or 2. This is referred to as orthogonal covering(OC).

Multiple terminals may be multiplexed by a code division multiplexing(CDM) scheme by using the CS resources in the frequency domain and theOC resources in the time domain described above. That is, ACK/NACKinformation and RSs of a lot of terminals may be multiplexed on the samePUCCH RB.

In respect to the time-domain spread CDM, the number of spreading codessupported with respect to the ACK/NACK information is limited by thenumber of RS symbols. That is, since the number of RS transmittingSC-FDMA symbols is smaller than that of ACK/NACK informationtransmitting SC-FDMA symbols, the multiplexing capacity of the RS issmaller than that of the ACK/NACK information.

For example, in the case of the general CP, the ACK/NACK information maybe transmitted in four symbols and not 4 but 3 orthogonal spreadingcodes are used for the ACK/NACK information and the reason is that thenumber of RS transmitting symbols is limited to 3 to use only 3orthogonal spreading codes for the RS.

In the case of the subframe of the general CP, when 3 symbols are usedfor transmitting the RS and 4 symbols are used for transmitting theACK/NACK information in one slot, for example, if 6 CSs in the frequencydomain and 3 orthogonal cover (OC) resources may be used, HARQacknowledgement responses from a total of 18 different terminals may bemultiplexed in one PUCCH RB. In the case of the subframe of the extendedCP, when 2 symbols are used for transmitting the RS and 4 symbols areused for transmitting the ACK/NACK information in one slot, for example,if 6 CSs in the frequency domain and 2 orthogonal cover (OC) resourcesmay be used, the HARQ acknowledgement responses from a total of 12different terminals may be multiplexed in one PUCCH RB.

Next, PUCCH format 1 is described. The scheduling request (SR) istransmitted by a scheme in which the terminal requests scheduling ordoes not request the scheduling. An SR channel reuses an ACK/NACKchannel structure in PUCCH format 1a/1b and is configured by an on-offkeying (OOK) scheme based on an ACK/NACK channel design. In the SRchannel, the reference signal is not transmitted. Therefore, in the caseof the general CP, a sequence having a length of 7 is used and in thecase of the extended CP, a sequence having a length of 6 is used.Different cyclic shifts (CSs) or orthogonal covers (OCs) may beallocated to the SR and the ACK/NACK. That is, the terminal transmitsthe HARQ ACK/NACK through a resource allocated for the SR in order totransmit a positive SR. The terminal transmits the HARQ ACK/NACK througha resource allocated for the ACK/NACK in order to transmit a negativeSR.

Next, an enhanced-PUCCH (e-PUCCH) format is described. An e-PUCCH maycorrespond to PUCCH format 3 of an LTE-A system. A block spreadingtechnique may be applied to ACK/NACK transmission using PUCCH format 3.

The block spreading technique is a scheme that modulates transmission ofthe control signal by using the SC-FDMA scheme unlike the existing PUCCHformat 1 series or 2 series. As illustrated in FIG. 8, a symbol sequencemay be spread and transmitted on the time domain by using an orthogonalcover code (OCC). The control signals of the plurality of terminals maybe multiplexed on the same RB by using the OCC. In the case of PUCCHformat 2 described above, one symbol sequence is transmitted throughoutthe time domain and the control signals of the plurality of terminalsare multiplexed by using the cyclic shift (CS) of the CAZAC sequence,while in the case of a block spreading based on PUCCH format (forexample, PUCCH format 3), one symbol sequence is transmitted throughoutthe frequency domain and the control signals of the plurality ofterminals are multiplexed by using the time domain spreading using theOCC.

FIG. 8 illustrates one example of generating and transmitting 5 SC-FDMAsymbols during one slot in the wireless communication system to whichthe present invention can be applied.

In FIG. 8, an example of generating and transmitting 5 SC-FDMA symbols(that is, data part) by using an OCC having the length of 5(alternatively, SF=5) in one symbol sequence during one slot. In thiscase, two RS symbols may be used during one slot.

In the example of FIG. 8, the RS symbol may be generated from a CAZACsequence to which a specific cyclic shift value is applied andtransmitted in a type in which a predetermined OCC is applied(alternatively, multiplied) throughout a plurality of RS symbols.Further, in the example of FIG. 8, when it is assumed that 12 modulatedsymbols are used for each OFDM symbol (alternatively, SC-FDMA symbol)and the respective modulated symbols are generated by QPSK, the maximumbit number which may be transmitted in one slot becomes 24 bits (=12×2).Accordingly, the bit number which is transmittable by two slots becomesa total of 48 bits. When a PUCCH channel structure of the blockspreading scheme is used, control information having an extended sizemay be transmitted as compared with the existing PUCCH format 1 seriesand 2 series.

General Carrier Aggregation

A communication environment considered in embodiments of the presentinvention includes multi-carrier supporting environments. That is, amulti-carrier system or a carrier aggregation system used in the presentinvention means a system that aggregates and uses one or more componentcarriers (CCs) having a smaller bandwidth smaller than a target band atthe time of configuring a target wideband in order to support awideband.

In the present invention, multi-carriers mean aggregation of(alternatively, carrier aggregation) of carriers and in this case, theaggregation of the carriers means both aggregation between continuouscarriers and aggregation between non-contiguous carriers. Further, thenumber of component carriers aggregated between the downlink and theuplink may be differently set. A case in which the number of downlinkcomponent carriers (hereinafter, referred to as ‘DL CC’) and the numberof uplink component carriers (hereinafter, referred to as ‘UL CC’) arethe same as each other is referred to as symmetric aggregation and acase in which the number of downlink component carriers and the numberof uplink component carriers are different from each other is referredto as asymmetric aggregation. The carrier aggregation may be usedmixedly with a term such as the carrier aggregation, the bandwidthaggregation, spectrum aggregation, or the like.

The carrier aggregation configured by combining two or more componentcarriers aims at supporting up to a bandwidth of 100 MHz in the LTE-Asystem. When one or more carriers having the bandwidth than the targetband are combined, the bandwidth of the carriers to be combined may belimited to a bandwidth used in the existing system in order to maintainbackward compatibility with the existing IMT system. For example, theexisting 3GPP LTE system supports bandwidths of 1.4, 3, 5, 10, 15, and20 MHz and a 3GPP LTE-advanced system (that is, LTE-A) may be configuredto support a bandwidth larger than 20 MHz by using on the bandwidth forcompatibility with the existing system. Further, the carrier aggregationsystem used in the preset invention may be configured to support thecarrier aggregation by defining a new bandwidth regardless of thebandwidth used in the existing system.

The LTE-A system uses a concept of the cell in order to manage a radioresource.

The carrier aggregation environment may be called a multi-cellenvironment. The cell is defined as a combination of a pair of adownlink resource (DL CC) and an uplink resource (UL CC), but the uplinkresource is not required. Therefore, the cell may be constituted by onlythe downlink resource or both the downlink resource and the uplinkresource. When a specific terminal has only one configured serving cell,the cell may have one DL CC and one UL CC, but when the specificterminal has two or more configured serving cells, the cell has DL CCsas many as the cells and the number of UL CCs may be equal to or smallerthan the number of DL CCs.

Alternatively, contrary to this, the DL CC and the UL CC may beconfigured. That is, when the specific terminal has multiple configuredserving cells, a carrier aggregation environment having UL CCs more thanDL CCs may also be supported. That is, the carrier aggregation may beappreciated as aggregation of two or more cells having different carrierfrequencies (center frequencies). Herein, the described ‘cell’ needs tobe distinguished from a cell as an area covered by the base stationwhich is generally used.

The cell used in the LTE-A system includes a primary cell (PCell) and asecondary cell (SCell. The P cell and the S cell may be used as theserving cell. In a terminal which is in an RRC_CONNECTED state, but doesnot have the configured carrier aggregation or does not support thecarrier aggregation, only one serving constituted by only the P cell ispresent. On the contrary, in a terminal which is in the RRC_CONNECTEDstate and has the configured carrier aggregation, one or more servingcells may be present and the P cell and one or more S cells are includedin all serving cells.

The serving cell (P cell and S cell) may be configured through an RRCparameter. PhysCellId as a physical layer identifier of the cell hasinteger values of 0 to 503. SCellIndex as a short identifier used toidentify the S cell has integer values of 1 to 7. ServCellIndex as ashort identifier used to identify the serving cell (P cell or S cell)has the integer values of 0 to 7. The value of 0 is applied to the Pcell and SCellIndex is previously granted for application to the S cell.That is, a cell having a smallest cell ID (alternatively, cell index) inServCellIndex becomes the P cell.

The P cell means a cell that operates on a primary frequency(alternatively, primary CC). The terminal may be used to perform aninitial connection establishment process or a connectionre-establishment process and may be designated as a cell indicatedduring a handover process. Further, the P cell means a cell whichbecomes the center of control associated communication among servingcells configured in the carrier aggregation environment. That is, theterminal may be allocated with and transmit the PUCCH only in the P cellthereof and use only the P cell to acquire the system information orchange a monitoring procedure. An evolved universal terrestrial radioaccess (E-UTRAN) may change only the P cell for the handover procedureto the terminal supporting the carrier aggregation environment by usingan RRC connection reconfiguration message (RRCConnectionReconfigutaion)message of an upper layer including mobile control information(mobilityControlInfo).

The S cell means a cell that operates on a secondary frequency(alternatively, secondary CC). Only one P cell may be allocated to aspecific terminal and one or more S cells may be allocated to thespecific terminal. The S cell may be configured after RRC connectionestablishment is achieved and used for providing an additional radioresource. The PUCCH is not present in residual cells other than the Pcell, that is, the S cells among the serving cells configured in thecarrier aggregation environment. The E-UTRAN may provide all systeminformation associated with a related cell which is in an RRC_CONNECTEDstate through a dedicated signal at the time of adding the S cells tothe terminal that supports the carrier aggregation environment. A changeof the system information may be controlled by releasing and adding therelated S cell and in this case, the RRC connection reconfiguration(RRCConnectionReconfigutaion) message of the upper layer may be used.The E-UTRAN may perform having different parameters for each terminalrather than broadcasting in the related S cell.

After an initial security activation process starts, the E-UTRAN addsthe S cells to the P cell initially configured during the connectionestablishment process to configure a network including one or more Scells. In the carrier aggregation environment, the P cell and the S cellmay operate as the respective component carriers. In an embodimentdescribed below, the primary component carrier (PCC) may be used as thesame meaning as the P cell and the secondary component carrier (SCC) maybe used as the same meaning as the S cell.

FIG. 9 illustrates examples of a component carrier and carrieraggregation in the wireless communication system to which the presentinvention can be applied.

FIG. 9a illustrates a single carrier structure used in an LTE system.The component carrier includes the DL CC and the UL CC. One componentcarrier may have a frequency range of 20 MHz.

FIG. 9b illustrates a carrier aggregation structure used in the LTEsystem. In the case of FIG. 9b , a case is illustrated, in which threecomponent carriers having a frequency magnitude of 20 MHz are combined.Each of three DL CCs and three UL CCs is provided, but the number of DLCCs and the number of UL CCs are not limited. In the case of carrieraggregation, the terminal may simultaneously monitor three CCs, andreceive downlink signal/data and transmit uplink signal/data.

When N DL CCs are managed in a specific cell, the network may allocate M(M≤N) DL CCs to the terminal. In this case, the terminal may monitoronly M limited DL CCs and receive the DL signal. Further, the networkgives L (L≤M≤N) DL CCs to allocate a primary DL CC to the terminal andin this case, UE needs to particularly monitor L DL CCs. Such a schememay be similarly applied even to uplink transmission.

A linkage between a carrier frequency (alternatively, DL CC) of thedownlink resource and a carrier frequency (alternatively, UL CC) of theuplink resource may be indicated by an upper-layer message such as theRRC message or the system information. For example, a combination of theDL resource and the UL resource may be configured by a linkage definedby system information block type 2 (SIB2). In detail, the linkage maymean a mapping relationship between the DL CC in which the PDCCHtransporting a UL grant and a UL CC using the UL grant and mean amapping relationship between the DL CC (alternatively, UL CC) in whichdata for the HARQ is transmitted and the UL CC (alternatively, DL CC) inwhich the HARQ ACK/NACK signal is transmitted.

Cross Carrier Scheduling

In the carrier aggregation system, in terms of scheduling for thecarrier or the serving cell, two types of a self-scheduling method and across carrier scheduling method are provided. The cross carrierscheduling may be called cross component carrier scheduling or crosscell scheduling.

The cross carrier scheduling means transmitting the PDCCH (DL grant) andthe PDSCH to different respective DL CCs or transmitting the PUSCHtransmitted according to the PDCCH (UL grant) transmitted in the DL CCthrough other UL CC other than a UL CC linked with the DL CC receivingthe UL grant.

Whether to perform the cross carrier scheduling may be UE-specificallyactivated or deactivated and semi-statically known for each terminalthrough the upper-layer signaling (for example, RRC signaling).

When the cross carrier scheduling is activated, a carrier indicatorfield (CIF) indicating through which DL/UL CC the PDSCH/PUSCH thePDSCH/PUSCH indicated by the corresponding PDCCH is transmitted isrequired. For example, the PDCCH may allocate the PDSCH resource or thePUSCH resource to one of multiple component carriers by using the CIF.That is, the CIF is set when the PDSCH or PUSCH resource is allocated toone of DL/UL CCs in which the PDCCH on the DL CC is multiply aggregated.In this case, a DCI format of LTE-A Release-8 may extend according tothe CIF. In this case, the set CIF may be fixed to a 3-bit field and theposition of the set CIF may be fixed regardless of the size of the DCIformat. Further, a PDCCH structure (the same coding and the same CCEbased resource mapping) of the LTE-A Release-8 may be reused.

On the contrary, when the PDCCH on the DL CC allocates the PDSCHresource on the same DL CC or allocates the PUSCH resource on a UL CCwhich is singly linked, the CIF is not set. In this case, the same PDCCHstructure (the same coding and the same CCE based resource mapping) andDCI format as the LTE-A Release-8 may be used.

When the cross carrier scheduling is possible, the terminal needs tomonitor PDCCHs for a plurality of DCIs in a control region of amonitoring CC according to a transmission mode and/or a bandwidth foreach CC. Therefore, a configuration and PDCCH monitoring of a searchspace which may support monitoring the PDCCHs for the plurality of DCIsare required.

In the carrier aggregation system, a terminal DL CC aggregate representsan aggregate of DL CCs in which the terminal is scheduled to receive thePDSCH and a terminal UL CC aggregate represents an aggregate of UL CCsin which the terminal is scheduled to transmit the PUSCH. Further, aPDCCH monitoring set represents a set of one or more DL CCs that performthe PDCCH monitoring. The PDCCH monitoring set may be the same as theterminal DL CC set or a subset of the terminal DL CC set. The PDCCHmonitoring set may include at least any one of DL CCs in the terminal DLCC set. Alternatively, the PDCCH monitoring set may be definedseparately regardless of the terminal DL CC set. The DL CCs included inthe PDCCH monitoring set may be configured in such a manner thatself-scheduling for the linked UL CC is continuously available. Theterminal DL CC set, the terminal UL CC set, and the PDCCH monitoring setmay be configured UE-specifically, UE group-specifically, orcell-specifically.

When the cross carrier scheduling is deactivated, the deactivation ofthe cross carrier scheduling means that the PDCCH monitoring setcontinuously means the terminal DL CC set and in this case, anindication such as separate signaling for the PDCCH monitoring set isnot required. However, when the cross carrier scheduling is activated,the PDCCH monitoring set is preferably defined in the terminal DL CCset. That is, the base station transmits the PDCCH through only thePDCCH monitoring set in order to schedule the PDSCH or PUSCH for theterminal.

FIG. 10 illustrates one example of a subframe structure depending oncross carrier scheduling in the wireless communication system to whichthe present invention can be applied.

Referring to FIG. 10, a case is illustrated, in which three DL CCs areassociated with a DL subframe for an LTE-A terminal and DL CC ‘A’ isconfigured as a PDCCH monitoring DL CC. When the CIF is not used, eachDL CC may transmit the PDCCH scheduling the PDSCH thereof without theCIF. On the contrary, when the CIF is used through the upper-layersignaling, only one DL CC ‘A’ may transmit the PDCCH scheduling thePDSCH thereof or the PDSCH of another CC by using the CIF. In this case,DL CC ‘B’ and ‘C’ in which the PDCCH monitoring DL CC is not configureddoes not transmit the PDCCH.

General ACK/NACK Multiplexing Method

In a situation in which the terminal simultaneously needs to transmitmultiple ACKs/NACKs corresponding to multiple data units received froman eNB, an ACK/NACK mulplexign method based on PUCCH resource selectionmay be considered in order to maintain a single-frequency characteristicof the ACK/NACK signal and reduce ACK/NACK transmission power.

Together with ACK/NACK multiplexing, contents of ACK/NACK responses formultiple data units may be identified by combining a PUCCH resource anda resource of QPSK modulation symbols used for actual ACK/NACKtransmission.

For example, when one PUCCH resource may transmit 4 bits and four dataunits may be maximally transmitted, an ACK/NACK result may be identifiedin the eNB as shown in Table 3 given below.

TABLE 3 HARQ-ACK(0), HARQ-ACK(1), HARQ-ACK(2), HARQ-ACK(3) n_(PUCCH) ⁽¹⁾b(0), b(1) ACK, ACK, ACK, ACK n_(PUCCH, 1) ⁽¹⁾ 1, 1 ACK, ACK, ACK,NACK/DTX n_(PUCCH, 1) ⁽¹⁾ 1, 0 NACK/DTX, NACK/DTX, NACK, DTXn_(PUCCH, 2) ⁽¹⁾ 1, 1 ACK, ACK, NACK/DTX, ACK n_(PUCCH, 1) ⁽¹⁾ 1, 0NACK, DTX, DTX, DTX n_(PUCCH, 0) ⁽¹⁾ 1, 0 ACK, ACK, NACK/DTX, NACK/DTXn_(PUCCH, 1) ⁽¹⁾ 1, 0 ACK, NACK/DTX, ACK, ACK n_(PUCCH, 3) ⁽¹⁾ 0, 1NACK/DTX, NACK/DTX, NACK/DTX, NACK n_(PUCCH, 3) ⁽¹⁾ 1, 1 ACK, NACK/DTX,ACK, NACK/DTX n_(PUCCH, 2) ⁽¹⁾ 0, 1 ACK, NACK/DTX, NACK/DTX, ACKn_(PUCCH, 0) ⁽¹⁾ 0, 1 ACK, NACK/DTX, NACK/DTX, NACK/DTX n_(PUCCH, 0) ⁽¹⁾1, 1 NACK/DTX, ACK, ACK, ACK n_(PUCCH, 3) ⁽¹⁾ 0, 1 NACK/DTX, NACK, DTX,DTX n_(PUCCH, 1) ⁽¹⁾ 0, 0 NACK/DTX, ACK, ACK, NACK/DTX n_(PUCCH, 2) ⁽¹⁾1, 0 NACK/DTX, ACK, NACK/DTX, ACK n_(PUCCH, 3) ⁽¹⁾ 1, 0 NACK/DTX, ACK,NACK/DTX, NACK/DTX n_(PUCCH, 1) ⁽¹⁾ 0, 1 NACK/DTX, NACK/DTX, ACK, ACKn_(PUCCH, 3) ⁽¹⁾ 0, 1 NACK/DTX, NACK/DTX, ACK, NACK/DTX n_(PUCCH, 2) ⁽¹⁾0, 0 NACK/DTX, NACK/DTX, NACK/DTX, ACK n_(PUCCH, 3) ⁽¹⁾ 0, 0 DTX, DTX,DTX, DTX N/A N/A

In Table 3 given above, HARQ-ACK(i) represents an ACK/NACK result for ani-th data unit. In Table 3 given above, discontinuous transmission (DTX)means that there is no data unit to be transmitted for the correspondingHARQ-ACK(i) or that the terminal may not detect the data unitcorresponding to the HARQ-ACK(i).

According to Table 3 given above, a maximum of four PUCCH resources(n_(PUCCH,0) ⁽¹⁾, n_(PUCCH,1) ⁽¹⁾, n_(PUCCH,2) ⁽¹⁾, and n_(PUCCH,3) ⁽¹⁾)are provided and b(0) and b(1) are two bits transmitted by using aselected PUCCH.

For example, when the terminal successfully receives all of four dataunits, the terminal transmits 2 bits (1,1) by using n_(PUCCH,1) ⁽¹⁾.

When the terminal fails to decoding in first and third data units andsucceeds in decoding in second and fourth data units, the terminaltransmits bits (1,0) by using n_(PUCCH,3) ⁽¹⁾.

In ACK/NACK channel selection, when there is at least one ACK, the NACKand the DTX are coupled with each other. The reason is that acombination of the PUCCH resource and the QPSK symbol may not allACK/NACK states. However, when there is no ACK, the DTX is decoupledfrom the NACK.

In this case, the PUCCH resource linked to the data unit correspondingto one definite NACK may also be reserved to transmit signals ofmultiple ACKs/NACKs.

Validation of PDCCH for Semi-Persistent Scheduling

Semi-persistent scheduling (SPS) is a scheduling scheme that allocatesthe resource to the terminal to be persistently maintained during aspecific time interval.

When a predetermined amount of data is transmitted for a specific timelike a voice over Internet protocol (VoIP), since the controlinformation need not be transmitted every data transmission interval forthe resource allocation, the waste of the control information may bereduced by using the SPS scheme. In a so-called semi-persistentscheduling (SPS) method, a time resource domain in which the resourcemay be allocated to the terminal is preferentially allocated.

In this case, in a semi-persistent allocation method, a time resourcedomain allocated to a specific terminal may be configured to haveperiodicity. Then, a frequency resource domain is allocated as necessaryto complete allocation of the time-frequency resource. Allocating thefrequency resource domain may be designated as so-called activation.When the semi-persistent allocation method is used, since the resourceallocation is maintained during a predetermined period by one-timesignaling, the resource need not be repeatedly allocated, and as aresult, signaling overhead may be reduced.

Thereafter, since the resource allocation to the terminal is notrequired, signaling for releasing the frequency resource allocation maybe transmitted from the base station to the terminal. Releasing theallocation of the frequency resource domain may be designated asdeactivation.

In current LTE, in which subframes the SPS is first transmitted/receivedthrough radio resource control (RRC) signaling for the SPS for theuplink and/or downlink is announced to the terminal. That is, the timeresource is preferentially designated among the time and frequencyresources allocated for the SPS through the RRC signaling. In order toannounce a usable subframe, for example, a period and an offset of thesubframe may be announced. However, since the terminal is allocated withonly the time resource domain through the RRC signaling, even though theterminal receives the RRC signaling, the terminal does not immediatelyperform transmission and reception by the SPS and the terminal allocatesthe frequency resource domain as necessary to complete the allocation ofthe time-frequency resource. Allocating the frequency resource domainmay be designated as deactivation and releasing the allocation of thefrequency resource domain may be designated as deactivation.

Therefore, the terminal receives the PDCCH indicating the activation andthereafter, allocate the frequency resource according to RB allocationinformation included in the received PDCCH and applies modulation andcode rate depending on modulation and coding scheme (MCS) information tostart transmission and reception according to the period and the offsetof the subframe allocated through the RRC signaling.

Next, when the terminal receives the PDCCH announcing the deactivationfrom the base station, the terminal stops transmission and reception.When the terminal receives the PDCCH indicating the activation orreactivation after stopping the transmission and reception, the terminalresumes the transmission and reception again with the period and theoffset of the subframe allocated through the RRC signaling by using theRC allocation, the MCS, and the like designated by the PDCCH. That is,the time resource is performed through the RRC signaling, but the signalmay be actually transmitted and received after receiving the PDCCHindicating the activation and reactivation of the SPS and the signaltransmission and reception stop after receiving the PDCCH indicating thedeactivation of the SPS.

When all conditions described below are satisfied, the terminal mayvalidate a PDCCH including an SPS indication. First, a CRC parity bitadded for a PDCCH payload needs to be scrambled with an SPS C-RNTI andsecond, a new data indicator (NDI) field needs to be set to 0. Herein,in the case of DCI formats 2, 2A, 2B, and 2C, the new data indicatorfield indicates one activated transmission block.

In addition, when each field used in the DCI format is set according toTables 4 and 5 given below, the validation is completed. When thevalidation is completed, the terminal recognizes that received DCIinformation is valid SPS activation or deactivation (alternatively,release). On the contrary, when the validation is not completed, theterminal recognizes that a non-matching CRC is included in the receivedDCI format.

Table 4 shows a field for validating the PDCCH indicating the SPSactivation.

TABLE 4 DCI format DCI format DCI format 0 1/1A 2/2A/2B TPC command forset to ‘00’ N/A N/A scheduled PUSCH Cyclic shift DM RS set to ‘000’ N/AN/A Modulation and MSB is set N/A N/A coding scheme to ‘0’ andredundancy version HARQ process N/A FDD: set to ‘000’ FDD: set to ‘000’number TDD: set to ‘0000’ TDD: set to ‘0000’ Modulation and N/A MSB isFor the enabled coding scheme set to ‘0’ transport block: MSB is set to‘0’ Redundancy N/A set to ‘0’ For the enabled version transport block:set to ‘00’

Table 5 shows a field for validating the PDCCH indicating the SPSdeactivation (alternatively, release).

TABLE 5 DCI format 0 DCI format 1A TPC command for set to ‘00’ N/Ascheduled PUSCH Cyclic shift DM RS set to ‘000’ N/A Modulation andcoding set to ‘11111’ N/A scheme and redundancy version Resource blockassignment Set to all ‘1’s N/A and hopping resource allocation HARQprocess number N/A FDD: set to ‘000’ TDD: set to ‘0000’ Modulation andcoding N/A set to ‘11111’ scheme Redundancy version N/A set to ‘00’Resource block assignment N/A Set to all ‘1’s

When the DCI format indicates SPS downlink scheduling activation, a TPCcommand value for the PUCCH field may be used as indexes indicating fourPUCCH resource values set by the upper layer.

PUCCH Piggybacking in Rel-8 LTE

FIG. 11 illustrates one example of transport channel processing of aUL-SCH in the wireless communication system to which the presentinvention can be applied.

In a 3GPP LTE system (=E-UTRA, Rel. 8), in the case of the UL, singlecarrier transmission having an excellent peak-to-average power ratio(PAPR) or cubic metric (CM) characteristic which influences theperformance of a power amplifier is maintained for efficient utilizationof the power amplifier of the terminal. That is, in the case oftransmitting the PUSCH of the existing LTE system, data to betransmitted may maintain the single carrier characteristic throughDFT-precoding and in the case of transmitting the PUCCH, information istransmitted while being loaded on a sequence having the single carriercharacteristic to maintain the single carrier characteristic. However,when the data to be DFT-precoded is non-contiguously allocated to afrequency axis or the PUSCH and the PUCCH are simultaneouslytransmitted, the single carrier characteristic deteriorates. Therefore,when the PUSCH is transmitted in the same subframe as the transmissionof the PUCCH as illustrated in FIG. 11, uplink control information (UCI)to be transmitted to the PUCCH is transmitted (piggyback) together withdata through the PUSCH.

Since the PUCCH and the PUSCH may not be simultaneously transmitted asdescribed above, the existing LTE terminal uses a method thatmultiplexes uplink control information (UCI) (CQI/PMI, HARQ-ACK, RI, andthe like) to the PUSCH region in a subframe in which the PUSCH istransmitted.

As one example, when the channel quality indicator (CQI) and/orprecoding matrix indicator (PMI) needs to be transmitted in a subframeallocated to transmit the PUSCH, UL-SCH data and the CQI/PMI aremultiplexed after DFT-spreading to transmit both control information anddata. In this case, the UL-SCH data is rate-matched by considering aCQI/PMI resource. Further, a scheme is used, in which the controlinformation such as the HARQ ACK, the RI, and the like punctures theUL-SCH data to be multiplexed to the PUSCH region.

FIG. 12 illustrates one example of a signal processing process of anuplink share channel of a transport channel in the wirelesscommunication system to which the present invention can be applied.

Herein, the signal processing process of the uplink share channel(hereinafter, referred to as “UL-SCH”) may be applied to one or moretransport channels or control information types.

Referring to FIG. 12, the UL-SCH transfers data to a coding unit in theform of a transport block (TB) once every a transmission time interval(TTI).

A CRC parity bit p₀, p₁, p₂, p₃, . . . , p_(L-1) is attached to a bit ofthe transport block received from the upper layer (S120). In this case,A represents the size of the transport block and L represents the numberof parity bits. Input bits to which the CRC is attached are shown in b₀,b₁, b₂, b₃, . . . , b_(B-1). In this case, B represents the number ofbits of the transport block including the CRC.

b₀, b₁, b₂, b₃, . . . , b_(B-1) is segmented into multiple code blocks(CBs) according to the size of the TB and the CRC is attached tomultiple segmented CBs (S121). Bits after the code block segmentationand the CRC attachment are shown in c_(r0), c_(r1), c_(r2), c_(r3), . .. , c_(r(K) _(r) ⁻¹⁾. Herein, r represents No. (r=0, . . . , C−1) of thecode block and Kr represents the bit number depending on the code blockr. Further, C represents the total number of code blocks.

Subsequently, channel coding is performed (S122). Output bits after thechannel coding are shown in d_(r0) ^((i)), d_(r1) ^((i)), d_(r2) ^((i)),d_(r3) ^((i)), . . . , d_(r(D) _(r) ⁻¹⁾ ^((i)). In this case, irepresents an encoded stream index and may have a value of 0, 1, or 2.Dr represents the number of bits of the i-th encoded stream for the codeblock r. r represents the code block number (r=0, . . . , C−1) and Crepresents the total number of code blocks. Each code block may beencoded by turbo coding.

Subsequently, rate matching is performed (S123). Bits after the ratematching are shown in e_(r0), e_(r1), e_(r2), e_(r3), . . . , e_(r(E)_(r) ⁻¹⁾ In this case, r represents the code block number (r=0, . . . ,C−1) and C represents the total number of code blocks. Er represents thenumber of rate-matched bits of the r-th code block.

Subsequently, concatenation among the code blocks is performed again(S124). Bits after the concatenation of the code blocks is performed areshown in f₀, f₁, f₂, f₃, . . . , f_(G−1). In this case, G represents thetotal number of bits encoded for transmission and when the controlinformation is multiplexed with the UL-SCH, the number of bits used fortransmitting the control information is not included.

Meanwhile, when the control information is transmitted in the PUSCH,channel coding of the CQI/PMI, the RI, and the ACK/NACK which are thecontrol information is independently performed (S126, S127, and S128).Since different encoded symbols are allocated for transmitting eachcontrol information, the respective control information has differentcoding rates.

In time division duplex (TDD), as an ACK/NACK feedback mode, two modesof ACK/NACK bundling and ACK/NACK multiplexing are supported by anupper-layer configuration. ACK/NACK information bits for the ACK/NACKbundling are constituted by 1 bit or 2 bits and ACK/NACK informationbits for the ACK/NACK multiplexing are constituted by 1 to 4 bits.

After the concatenation among the code blocks in step S134, encoded bitsf₀, f₁, f₂, f₃, . . . , f_(G−1) of the UL-SCH data and encoded bits q₀,q₁, q₂, q₃, . . . , q_(N) _(L) _(·Q) _(CQI) ⁻¹ of the CQI/PMI aremultiplexed (S125). A multiplexed result of the data and the CQI/PMI isshown in to g ₀, g ₁, g ₂, g ₃, . . . , g _(H′−1). In this case, g _(i)(i=0, . . . , H′−1) represents a column vector having a length of(Q_(m)·N_(L)). H=(G+N_(L)·Q_(CQI)) and H′=H/(N_(L)·Q_(m)). N_(L)represents the number of layers mapped to a UL-SCH transport block and Hrepresents the total number of encoded bits allocated to N_(L) transportlayers mapped with the transport block for the UL-SCH data and theCQI/PMI information.

Subsequently, the multiplexed data and CQI/PMI, a channel encoded RI,and the ACK/NACK are channel-interleaved to generate an output signal(S129).

Reference Signal (RS)

In the wireless communication system, since the data is transmittedthrough the radio channel, the signal may be distorted duringtransmission. In order for the receiver side to accurately receive thedistorted signal, the distortion of the received signal needs to becorrected by using channel information. In order to detect the channelinformation, a signal transmitting method know by both the transmitterside and the receiver side and a method for detecting the channelinformation by using an distortion degree when the signal is transmittedthrough the channel are primarily used. The aforementioned signal isreferred to as a pilot signal or a reference signal (RS).

When the data is transmitted and received by using the MIMO antenna, achannel state between the transmitting antenna and the receiving antennaneed to be detected in order to accurately receive the signal.Therefore, the respective transmitting antennas need to have individualreference signals.

The downlink reference signal includes a common RS (CRS) shared by allterminals in one cell and a dedicated RS (DRS) for a specific terminal.Information for demodulation and channel measurement may be provided byusing the reference signals.

The receiver side (that is, terminal) measures the channel state fromthe CRS and feeds back the indicators associated with the channelquality, such as the channel quality indicator (CQI), the precodingmatrix index (PMI), and/or the rank indicator (RI) to the transmittingside (that is, base station). The CRS is also referred to as acell-specific RS. On the contrary, a reference signal associated with afeed-back of channel state information (CSI) may be defined as CSI-RS.

The DRS may be transmitted through resource elements when datademodulation on the PDSCH is required. The terminal may receive whetherthe DRS is present through the upper layer and is valid only when thecorresponding PDSCH is mapped. The DRS may be referred to as theUE-specific RS or the demodulation RS (DMRS).

FIG. 13 illustrates a reference signal pattern mapped to a downlinkresource block pair in the wireless communication system to which thepresent invention can be applied.

Referring to FIG. 13, as a wise in which the reference signal is mapped,the downlink resource block pair may be expressed by one subframe in thetimedomain×12 subcarriers in the frequency domain. That is, one resourceblock pair has a length of 14 OFDM symbols in the case of a normalcyclic prefix (CP) (FIG. 13a ) and a length of 12 OFDM symbols in thecase of an extended cyclic prefix (CP) (FIG. 13b ). Resource elements(REs) represented as ‘0’, ‘1’, ‘2’, and ‘3’ in a resource block latticemean the positions of the CRSs of antenna port indexes ‘0’, ‘1’, ‘2’,and ‘3’, respectively and resource elements represented as ‘D’ means theposition of the DRS.

Hereinafter, when the CRS is described in more detail, the CRS is usedto estimate a channel of a physical antenna and distributed in a wholefrequency band as the reference signal which may be commonly received byall terminals positioned in the cell. Further, the CRS may be used todemodulate the channel quality information (CSI) and data.

The CRS is defined as various formats according to an antenna array atthe transmitter side (base station). The 3GPP LTE system (for example,release-8) supports various antenna arrays and a downlink signaltransmitting side has three types of antenna arrays of three singletransmitting antennas, two transmitting antennas, and four transmittingantennas. When the base station uses the single transmitting antenna, areference signal for a single antenna port is arrayed. When the basestation uses two transmitting antennas, reference signals for twotransmitting antenna ports are arrayed by using a time divisionmultiplexing (TDM) scheme and/or a frequency division multiplexing (FDM)scheme. That is, different time resources and/or different frequencyresources are allocated to the reference signals for two antenna portswhich are distinguished from each other.

Moreover, when the base station uses four transmitting antennas,reference signals for four transmitting antenna ports are arrayed byusing the TDM and/or FDM scheme. Channel information measured by adownlink signal receiving side (terminal) may be used to demodulate datatransmitted by using a transmission scheme such as single transmittingantenna transmission, transmission diversity, closed-loop spatialmultiplexing, open-loop spatial multiplexing, or multi-user MIMO.

In the case where the MIMO antenna is supported, when the referencesignal is transmitted from a specific antenna port, the reference signalis transmitted to the positions of specific resource elements accordingto a pattern of the reference signal and not transmitted to thepositions of the specific resource elements for another antenna port.That is, reference signals among different antennas are not duplicatedwith each other.

A rule of mapping the CRS to the resource block is defined as below.

$\begin{matrix}{{k = {{6m} + {\left( {v + v_{shift}} \right){mod}{\mspace{11mu}\;}6}}}{l = \left\{ {{{\begin{matrix}{0,{N_{symb}^{DL} - 3}} & {{{if}\mspace{14mu} p} \in \left\{ {0,1} \right\}} \\1 & {{{if}\mspace{14mu} p} \in \left\{ {2,3} \right\}}\end{matrix}m} = 0},1,\ldots\mspace{14mu},{{{2 \cdot N_{RB}^{DL}} - {1m^{\prime}}} = {{m + N_{RB}^{\max,{DL}} - {N_{RB}^{DL}v}} = \left\{ {{\begin{matrix}0 & {{{if}\mspace{14mu} p} = {{0\mspace{14mu}{and}\mspace{14mu} l} = 0}} \\3 & {{{if}\mspace{14mu} p} = {{0\mspace{14mu}{and}\mspace{14mu} l} \neq 0}} \\3 & {{{if}\mspace{14mu} p} = {{1\mspace{14mu}{and}\mspace{14mu} l} = 0}} \\0 & {{{if}\mspace{14mu} p} = {{l\mspace{14mu}{and}\mspace{14mu} l} \neq 0}} \\{3\left( {n_{s}\mspace{14mu}{mod}\mspace{14mu} 2} \right)} & {{{if}\mspace{14mu} p} = 2} \\{3 + {3\left( {n_{s}\mspace{14mu}{mod}\mspace{14mu} 2} \right)}} & {{{if}\mspace{14mu} p} = 3}\end{matrix}v_{shift}^{\;}} = {N_{ID}^{cell}\mspace{14mu}{mod}\mspace{14mu} 6}} \right.}}} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Equation 1, k and l represent the subcarrier index and the symbolindex, respectively and p represents the antenna port. N_(symb) ^(DL)represents the number of OFDM symbols in one downlink slot and N_(RB)^(DL) represents the number of radio resources allocated to thedownlink. ns represents a slot index and, N_(ID) ^(cell) represents acell ID. mod represents an modulo operation. The position of thereference signal varies depending on the v_(shift) value in thefrequency domain. Since v_(shift) is subordinated to the cell ID, theposition of the reference signal has various frequency shift valuesaccording to the cell.

In more detail, the position of the CRS may be shifted in the frequencydomain according to the cell in order to improve channel estimationperformance through the CRS. For example, when the reference signal ispositioned at an interval of three subcarriers, reference signals in onecell are allocated to a 3k-th subcarrier and a reference signal inanother cell is allocated to a 3k+1-th subcarrier. In terms of oneantenna port, the reference signals are arrayed at an interval of sixresource elements in the frequency domain and separated from a referencesignal allocated to another antenna port at an interval of threeresource elements.

In the time domain, the reference signals are arrayed at a constantinterval from symbol index 0 of each slot. The time interval is defineddifferently according to a cyclic shift length. In the case of thenormal cyclic shift, the reference signal is positioned at symbolindexes 0 and 4 of the slot and in the case of the extended CP, thereference signal is positioned at symbol indexes 0 and 3 of the slot. Areference signal for an antenna port having a maximum value between twoantenna ports is defined in one OFDM symbol. Therefore, in the case oftransmission of four transmitting antennas, reference signals forreference signal antenna ports 0 and 1 are positioned at symbol indexes0 and 4 (symbol indexes 0 and 3 in the case of the extended CP) andreference signals for antenna ports 2 and 3 are positioned at symbolindex 1 of the slot. The positions of the reference signals for antennaports 2 and 3 in the frequency domain are exchanged with each other in asecond slot.

Hereinafter, when the DRS is described in more detail, the DRS is usedfor demodulating data. A precoding weight used for a specific terminalin the MIMO antenna transmission is used without a change in order toestimate a channel associated with and corresponding to a transmissionchannel transmitted in each transmitting antenna when the terminalreceives the reference signal.

The 3GPP LTE system (for example, release-8) supports a maximum of fourtransmitting antennas and a DRS for rank 1 beamforming is defined. TheDRS for the rank 1 beamforming also means a reference signal for antennaport index 5.

A rule of mapping the DRS to the resource block is defined as below.Equation 2 shows the case of the normal CP and Equation 3 shows the caseof the extended CP.

$\begin{matrix}{{k = {{\left( k^{\prime} \right){mod}\mspace{14mu} N_{sc}^{RB}} + {N_{sc}^{RB} \cdot n_{PRB}}}}{k^{\prime} = \left\{ {{\begin{matrix}{{4m^{\prime}} + v_{shift}} & {{{if}\mspace{14mu} l} \in \left\{ {2,3} \right\}} \\{{4m^{\prime}} + {\left( {2 + v_{shift}} \right){mod}\mspace{14mu} 4}} & {{{if}\mspace{14mu} l} \in \left\{ {5,6} \right\}}\end{matrix}l} = \left\{ {{\begin{matrix}3 & {l^{\prime} = 0} \\6 & {l^{\prime} = 1} \\2 & {l^{\prime} = 2} \\5 & {l^{\prime} = 3}\end{matrix}l^{\prime}} = \left\{ {{{\begin{matrix}{0,1} & {{{if}\mspace{14mu} n_{s}\mspace{14mu}{mod}\mspace{14mu} 2} = 0} \\{2,3} & {{{if}\mspace{14mu} n_{s}\mspace{14mu}{mod}\mspace{14mu} 2} = 1}\end{matrix}m^{\prime}} = 0},1,\ldots\mspace{14mu},{{{3N_{RB}^{PDSCH}} - {1v_{shift}}} = {N_{ID}^{cell}\mspace{14mu}{mod}\mspace{14mu} 3}}} \right.} \right.} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack \\{{k = {{\left( k^{\prime} \right)\mspace{14mu}{mod}\mspace{14mu} N_{sc}^{RB}} + {N_{sc}^{RB} \cdot n_{PRB}}}}k^{\prime} = \left\{ {{\begin{matrix}{{3m^{\prime}} + v_{shift}} & {{{if}\mspace{14mu} l} = 4} \\{{3m^{\prime}} + {\left( {2 + v_{shift}} \right){mod}\mspace{14mu} 3}} & {{{if}\mspace{14mu} l} = 1}\end{matrix}l} = \left\{ {{\begin{matrix}4 & {l^{\prime} \in \left\{ {0,2} \right\}} \\1 & {l^{\prime} = 1}\end{matrix}l^{\prime}} = \left\{ {{{\begin{matrix}0 & {{{if}\mspace{14mu} n_{s}\mspace{14mu}{mod}\mspace{14mu} 2} = 0} \\{1,2} & {{{if}\mspace{14mu} n_{s}\mspace{14mu}{mod}\mspace{14mu} 2} = 1}\end{matrix}m^{\prime}} = 0},1,\ldots\mspace{14mu},{{{4N_{RB}^{PDSCH}} - {1v_{shift}}} = {N_{ID}^{cell}\mspace{14mu}{mod}\mspace{11mu} 3}}} \right.} \right.} \right.} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

In Equations 2 and 3, k and l represent the subcarrier index and thesymbol index, respectively and p represents the antenna port. N_(sc)^(RB) represents the size of the resource block in the frequency domainand is expressed as the number of subcarriers. n_(PRB) represents thenumber of physical resource blocks. N_(RB) ^(PDSCH) represents afrequency band of the resource block for the PDSCH transmission. nsrepresents the slot index and N_(ID) ^(cell) represents the cell ID. modrepresents the modulo operation. The position of the reference signalvaries depending on the v_(shift) value in the frequency domain. Sincev_(shift) is subordinated to the cell ID, the position of the referencesignal has various frequency shift values according to the cell.

Sounding Reference Signal (SRS)

The SRS is primarily used for the channel quality measurement in orderto perform frequency-selective scheduling and is not associated withtransmission of the uplink data and/or control information. However, theSRS is not limited thereto and the SRS may be used for various otherpurposes for supporting improvement of power control and variousstart-up functions of terminals which have not been scheduled. Oneexample of the start-up function may include an initial modulation andcoding scheme (MCS), initial power control for data transmission, timingadvance, and frequency semi-selective scheduling. In this case, thefrequency semi-selective scheduling means scheduling that selectivelyallocates the frequency resource to the first slot of the subframe andallocates the frequency resource by pseudo-randomly hopping to anotherfrequency in the second slot.

Further, the SRS may be used for measuring the downlink channel qualityon the assumption that the radio channels between the uplink and thedownlink are reciprocal. The assumption is valid particularly in thetime division duplex in which the uplink and the downlink share the samefrequency spectrum and are divided in the time domain.

Subframes of the SRS transmitted by any terminal in the cell may beexpressed by a cell-specific broadcasting signal. A 4-bit cell-specific‘srsSubframeConfiguration’ parameter represents 15 available subframearrays in which the SRS may be transmitted through each radio frame. Bythe arrays, flexibility for adjustment of the SRS overhead is providedaccording to a deployment scenario.

A 16-th array among them completely turns off a switch of the SRS in thecell and is suitable primarily for a serving cell that serves high-speedterminals.

FIG. 14 illustrates an uplink subframe including a sounding referencesignal symbol in the wireless communication system to which the presentinvention can be applied.

Referring to FIG. 14, the SRS is continuously transmitted through a lastSC FDMA symbol on the arrayed subframes. Therefore, the SRS and the DMRSare positioned at different SC-FDMA symbols.

The PUSCH data transmission is not permitted in a specific SC-FDMAsymbol for the SRS transmission and consequently, when sounding overheadis highest, that is, even when the SRS symbol is included in allsubframes, the sounding overhead does not exceed approximately 7%.

Each SRS symbol is generated by a base sequence (random sequence or asequence set based on Zadoff-Ch (ZC)) associated with a given time wiseand a given frequency band and all terminals in the same cell use thesame base sequence. In this case, SRS transmissions from a plurality ofterminals in the same cell in the same frequency band and at the sametime are orthogonal to each other by different cyclic shifts of the basesequence to be distinguished from each other.

SRS sequences from different cells may be distinguished fro each otherby allocating different base sequences to respective cells, butorthogonality among different base sequences is not assured.

Coordinated Multi-Point Transmission and Reception (COMP)

According to a demand of LTE-advanced, CoMP transmission is proposed inorder to improve the performance of the system. The CoMP is also calledco-MIMO, collaborative MIMO, network MIMO, and the like. It isanticipated that the CoMP will improves the performance of the terminalpositioned at a cell edge and improve an average throughput of the cell(sector).

In general, inter-cell interference decreases the performance and theaverage cell (sector) efficiency of the terminal positioned at the celledge in a multi-cell environment in which a frequency reuse index is 1.In order to alleviate the inter-cell interference, the LTE system adoptsa simple passive method such as fractional frequency reuse (FFR) in theLTE system so that the terminal positioned at the cell edge hasappropriate performance efficiency in an interference-limitedenvironment. However, a method that reuses the inter-cell interferenceor alleviates the inter-cell interference as a signal (desired signal)which the terminal needs to receive is more preferable instead ofreduction of the use of the frequency resource for each cell. The CoMPtransmission scheme may be adopted in order to achieve theaforementioned object.

The CoMP scheme which may be applied to the downlink may be classifiedinto a joint processing (JP) scheme and a coordinatedscheduling/beamforming (CS/CB) scheme.

In the JP scheme, the data may be used at each point (base station) in aCoMP wise. The CoMP wise means a set of base stations used in the CoMPscheme. The JP scheme may be again classified into a joint transmissionscheme and a dynamic cell selection scheme.

The joint transmission scheme means a scheme in which the signal issimultaneously transmitted through a plurality of points which are allor fractional points in the CoMP wise. That is, data transmitted to asingle terminal may be simultaneously transmitted from a plurality oftransmission points. Through the joint transmission scheme, the qualityof the signal transmitted to the terminal may be improved regardless ofcoherently or non-coherently and interference with another terminal maybe actively removed.

The dynamic cell selection scheme means a scheme in which the signal istransmitted from the single point through the PDSCH in the CoMP wise.That is, data transmitted to the single terminal at a specific time istransmitted from the single point and data is not transmitted to theterminal at another point in the CoMP wise. The point that transmits thedata to the terminal may be dynamically selected.

According to the CS/CB scheme, the CoMP wise performs beamformingthrough coordination for transmitting the data to the single terminal.That is, the data is transmitted to the terminal only in the servingcell, but user scheduling/beamforming may be determined throughcoordination of a plurality of cells in the CoMP wise.

In the case of the uplink, CoMP reception means receiving the signaltransmitted by the coordination among a plurality of points which aregeographically separated. The CoMP scheme which may be applied to theuplink may be classified into a joint reception (JR) scheme and thecoordinated scheduling/beamforming (CS/CB) scheme.

The JR scheme means a scheme in which the plurality of points which areall or fractional points receives the signal transmitted through thePDSCH in the CoMP wise. In the CS/CB scheme, only the single pointreceives the signal transmitted through the PDSCH, but the userscheduling/beamforming may be determined through the coordination of theplurality of cells in the CoMP wise.

Cross-CC Scheduling and E-PDCCH Scheduling

In the existing 3GPP LTE Rel-10 system, if a cross-CC schedulingoperation is defined in an aggregation situation for a plurality of CCs(component carrier=(serving) cell), one CC may be preset to be able toreceive DL/UL scheduling from only one specific CC (i.e., scheduling CC)(namely, to be able to receive DL/UL grant PDCCH for the correspondingscheduled CC).

The corresponding scheduling CC may basically perform a DL/UL schedulingfor the scheduling CC itself.

In other words, the SS for the PDCCH scheduling the scheduling/scheduledCC in the cross-CC scheduling relation may come to exist in the controlchannel area of the scheduling CC.

Meanwhile, in the LTE system, CFDD DL carrier or TDD DL subframes usefirst n OFDM symbols of the subframe for PDCCH, PHICH, PCFICH and thelike which are physical channels for transmission of various controlinformations and use the rest of the OFDM symbols for PDSCHtransmission.

At this time, the number of symbols used for control channeltransmission in each subframe is dynamically transmitted to the UEthrough the physical channel such as PCFICH or is semi-staticallytransmitted to the UE through RRC signaling.

At this time, particularly, value n may be set by 1 to 4 symbolsdepending on the subframe characteristic and system characteristic(FDD/TDD, system bandwidth, etc.).

Meanwhile, in the existing LTE system, PDCCH, which is the physicalchannel for transmitting DL/UL scheduling and various controlinformation, may be transmitted through limited OFDM symbols.

Hence, the enhanced PDCCH (i.e., E-PDCCH), which is more freelymultiplexed in PDSCH and FDM/TDM scheme, may be introduced instead ofthe control channel which is transmitted through the OFDM which isseparated from the PDSCH like PDCCH.

FIG. 15 illustrates an example of multiplexing legacy PDCCH, PDSCH andE-PDCCH.

Here, the legacy PDCCH may be expressed as L-PDCCH.

FIG. 16 is a diagram illustrating a cell classification in a system thatsupports the carrier aggregation.

Referring to FIG. 16, a configured cell is a cell that should becarrier-merged based on a measurement report among the cells of a BS maybe configured for each terminal. The configured cell may reserve aresource for an ACK/NACK transmission for a PDSCH transmissionbeforehand. An activated cell is a cell that is configured to transmitPDSCH/PUSCH actually among the configured cells, and performs a ChannelState Information (CSI) report for the PDSCH/PUSCH transmission and aSounding Reference Signal (SRS) transmission. A de-activated cell is acell that does not transmit the PDSCH/PUSCH transmission by a command ofBS or a timer operation, may also stop the CSI report and the SRStransmission.

Synchronization Signal/Sequence (SS)

An SS includes a primary (P)-SS and a secondary (S)-SS, and correspondsto a signal used when a cell search is performed.

FIG. 17 is a diagram illustrating a frame structure used for an SStransmission in a system that uses a normal cyclic prefix (CP). FIG. 10is a diagram illustrating a frame structure used for an SS transmissionin a system that uses an extended CP.

The SS is transmitted in 0th subframe and second slot of the fifthsubframe, respectively, considering 4.6 ms which is a Global System forMobile communications (GSM) frame length for the easiness of aninter-Radio Access Technology (RAT) measurement, and a boundary for thecorresponding radio frame may be detected through the S-SS. The P-SS istransmitted in the last OFDM symbol of the corresponding slot and theS-SS is transmitted in the previous OFDM symbol of the P-SS.

The SS may transmit total 504 physical cell IDs through the combinationof 3 P-SSs and 168 S-SSs. In addition, the SS and the PBCH aretransmitted within 6 RBs at the center of a system bandwidth such that aterminal may detect or decode them regardless of the transmissionbandwidth.

A transmission diversity scheme of the SS is to use a single antennaport only and not separately used in a standard. That is, thetransmission diversity scheme of the SS uses a single antennatransmission or a transmission technique transparent to a terminal(e.g., Precoder Vector Switching (PVS), Time-Switched Transmit Diversity(TSTD) and Cyclic-Delay Diversity (CDD)).

1. P-SS Sign

Zadoff-Chu (ZC) sequence of length 63 in frequency domain may be definedand used as a sequence of the P-SS. The ZC sequence is defined byEquation 4, a sequence element, n=31 that corresponds to a DC subcarrieris punctured. In Equation 4, N_zc=63.

$\begin{matrix}{{d_{u\;}(n)} = e^{{- j}\frac{\pi\;{{un}{({n + 1})}}}{N_{ZC}}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

Among 6 RBs (=7 subcarriers) positioned at the center of frequencydomain, the remaining 9 subcarriers are always transmitted in zerovalue, which makes it easy to design a filter for performingsynchronization. In order to define total three P-SSs, the value ofu=29, 29 and 34 may be used in Equation 4. In this case, since 29 and 34have the conjugate symmetry relation, two correlations may besimultaneously performed. Here, the conjugate symmetry means Equation 5.By using the characteristics, it is possible to implement one shotcorrelater for u=29 and 43, and accordingly, about 33.3% of total amountof calculation may be decreased.d _(u)(n)=(−1)^(n)(d _(N) _(ZC) _(−u)(n))*,when N_(ZC) is even number.d _(u)(n)=(d _(N) _(ZC) _(−u)(n))*,  [Equation 5]when N_(ZC) is odd number.

2. S-SS Sign

The sequence used for the S-SS is combined with two interleavedm-sequences of length 31, and 168 cell group IDs are transmitted bycombining two sequences. The m-sequence as the SSS sequence is robust inthe frequency selective environment, and may be transformed to thehigh-speed m-sequence using the Fast Hadamard Transform, thereby theamount of operations being decreased. In addition, the configuration ofSSS using two short codes is proposed to decrease the amount ofoperations of terminal.

FIG. 19 is a diagram illustrating two sequences in a logical regionbeing mapped to a physical region by being interleaved.

Referring to FIG. 19, when two m-sequences used for generating the S-SSsign are defined by S1 and S2, in the case that the S-SS (S1, S2) ofsubframe 0 transmits the cell group ID with the combination, the S-SS(S2, S1) of subframe 5 is transmitted with being swapped, therebydistinguishing the 10 ms frame boundary. In this case, the SSS sign usesthe generation polynomial x5+x2+1, and total 31 signs may be generatedthrough the circular shift.

In order to improve the reception performance, two different P-SS-basedsequences are defined and scrambled to the S-SS, and scrambled to S1 andS2 with different sequences. Later, by defining the S1-based scramblingsign, the scrambling is performed to S2. In this case, the sign of S-SSis exchanged in a unit of 5 ms, but the P-SS-based scrambling sign isnot exchanged. The P-SS-based scrambling sign is defined by six circularshift versions according to the P-SS index in the m-sequence generatedfrom the generation polynomial x5+x2+1, and the S1-based scrambling signis defined by eight circular shift versions according to the S1 index inthe m-sequence generated from the generation polynomial x5+x4+x2+x1+1.

The contents below exemplify an asynchronous standard of the LTE system.

-   -   A terminal may monitor a downlink link quality based on a        cell-specific reference signal in order to detect a downlink        radio link quality of PCell.    -   A terminal may estimate a downlink radio link quality for the        purpose of monitoring the downlink radio link quality of PCell,        and may compare it with Q_out and Q_in, which are thresholds.    -   The threshold value Q_out may be defined as a level in which a        downlink radio link is not certainly received, and may        correspond to a block error rate 10% of a hypothetical PDCCH        transmission considering a PCFICH together with transmission        parameters.    -   The threshold value Q_in may be defined as a downlink radio link        quality level, which may be great and more certainly received        than Q_out, and may correspond to a block error rate 2% of a        hypothetical PDCCH transmission considering a PCFICH together        with transmission parameters.

Narrow Band (NB) LTE Cell Search

In the NB-LTE, although a cell search may follow the same rule as theLTE, there may be an appropriate modification in the sequence design inorder to increase the cell search capability.

FIG. 20 is a diagram illustrating a frame structure to which M-PSS andM-SSS are mapped. In the present disclosure, an M-PSS designates theP-SS in the NB-LTE, and an M-SSS designates the S-SS in the NB-LTE. TheM-PSS may also be designated to ‘NB-PSS’ and the M-SSS may also bedesignated to ‘NB-SSS’.

Referring to FIG. 20, in the case of the M-PSS, a single primarysynchronization sequence/signal may be used. (M-)PSS may be spanned upto 9 OFDM symbol lengths, and used for determining subframe timing aswell as an accurate frequency offset.

This may be interpreted that a terminal may use the M-PSS for acquiringtime and frequency synchronization with a BS. In this case, (M-)PSS maybe consecutively located in time domain.

The M-SSS may be spanned up to 6 OFDM symbol lengths, and used fordetermining the timing of a cell identifier and an M-frame. This may beinterpreted that a terminal may use the M-SSS for detecting anidentifier of a BS. In order to support the same number as the number ofcell identifier groups of the LTE, 504 different (M-)SSS may bedesigned.

Referring to the design of FIG. 20, the M-PSS and the M-SSS are repeatedevery 20 ms average, and existed/generated four times in a block of 80ms. In the subframes that include synchronization sequences, the M-PSSoccupies the last 9 OFDM symbols. The M-SSS occupies 6th, 7th, 10th,11th, 13th and 14th OFDM symbols in the case of normal CP, and occupies5th, 6th, 9th, 11th and 12th OFDM symbols in the case of extended CP.

The 9 OFDM symbols occupied by the M-PSS may be selected to support forthe in-band disposition between LTE carriers. This is because the firstthree OFDM symbols are used to carry a PDCCH in the hosting LTE systemand a subframe includes minimum twelve OFDM symbols (in the case ofextended CP).

In the hosting LTE system, a cell-specific reference signal (CRS) istransmitted, and the resource elements that correspond to the M-PSS maybe punctured in order to avoid a collision. In the NB-LTE, a specificposition of M-PSS/M-SSS may be determined to avoid a collision with manylegacy LTE signals such as the PDCCH, the PCFICH, the PHICH and/or theMBSFN.

In comparison with the LTE, the synchronization sequence design in theNB-LTE may be different.

This may be performed in order to attain a compromise between decreasedmemory consumption and faster synchronization in a terminal. Since theM-SSS is repeated four times in 80 ms duration, a slight designmodification for the M-SSS may be required in the 80 ms duration inorder to solve a timing uncertainty.

Structure of M-PSS and M-SSS

In the LTE, the PSS structure allows the low complexity design of timingand frequency offset measuring instrument, and the SSS is designed toacquire frame timing and to support unique 504 cell identifiers.

In the case of In-band and Guard-band of the LTE, the disposition of CPin the NB-LTE may be selected to match the CP in a hosting system. Inthe case of standalone, the extended CP may be used for matching atransmitter pulse shape for exerting the minimum damage to the hostingsystem (e.g., GSM).

A single M-PSS may be clearly stated in the N-LTE of the LTE. In theprocedure of PSS synchronization of the LTE, for each of PSSs, aspecific number of frequency speculations may be used for the coarseestimation of symbol timing and frequency offset.

Such an adaption of the procedure in the NB-LTE may increase the processcomplexity of a receiver according to the use of a plurality offrequency assumptions. In order to solve the problem, a sequenceresembling of the Zadoff-Chu sequence which is differentially decoded intime domain may be proposed for the M-PSS. Since the differentialdecoding is performed in a transmission process, the differentialdecoding may be performed during the processing time of a receiver.Consequently, a frequency offset may be transformed from the consecutiverotation for symbols to the fixed phase offset with respect to thecorresponding symbols.

FIG. 21 is a diagram illustrating a method for generating M-PSSaccording to an embodiment of the present invention.

Referring to FIG. 21, first, when starting with a basic sequence oflength 107 as a basis in order to generate an M-PSS, Equation 6 belowmay be obtained.

$\begin{matrix}{{{c(n)} = e^{- \frac{j\;\pi\;{{un}{({n + 1})}}}{N}}},{n = \left\{ {0,1,2,\ldots\mspace{14mu},106} \right\}}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

The basic sequence c(n) may be differentially decoded in order to obtaind(n) sequence as represented in Equation 7.d(n+1)=d(n)c(n),n={0,1,2, . . . ,106},d(0)=1,  [Equation 7]

The d(n) sequence is divided into 9 sub sequences, and each sub sequencehas a length 12 and a sampling rate of 130 kHz. The 120-point FFT isperformed for each of 9 sub sequences, and each sequence may beoversampled 128/12 times up to 1.92 MHz sampling rate using 128 IFFTzero padding. Consequently, each sub sequence may be mapped to 12subcarriers for 9 OFDM symbols, respectively.

Each of the sub sequences is mapped to a single OFDM symbol, and theM-PSS may occupy total 9 OFDM symbols since total 9 sub sequences areexisted. Total length of the M-PSS may be 1234(=(128+9)*9+1) when thenormal CP of 9 samples are used, and may be 1440 when the extended CP isused.

The M-PSS which is going to be actually used during the transmission isnot required to be generated every time using complex procedure in atransmitter/receiver in the same manner. The complexity coefficient(i.e., t_u(n)) that corresponds to the M-PSS may be generated inoffline, and directly stored in the transmitter/receiver. In addition,even in the case that the M-PSS is generated in 1.92 MHz, the occupationbandwidth may be 180 kHz.

Accordingly, in the case of performing the procedure related to time andfrequency offset measurements using the M-PSS in a receiver, thesampling rate of 192 kHz may be used for all cases. This maysignificantly decrease the complexity of receiver in the cell search.

In comparison with the LTE, the frequency in which the M-PSS isgenerated in the NB-LTE causes slightly greater overhead than the PSS inthe LTE. More particularly, the synchronization sequence used in the LTEoccupies 2.86% of the entire transmission resources, and thesynchronization sequence used in the NB-LTE occupies about 5.36% of theentire transmission resources. Such an additional overhead has an effectof decreasing memory consumption as well as the synchronization timethat leads to the improved battery life and the lower device price.

The M-SSS is designed in frequency domain and occupies 12 subcarriers ineach of 6 OFDM symbols. Accordingly, the number of resource elementsdedicated to the M-SSS may be 72. The M-SSS includes the ZC sequence ofa single length 61 which are padded by eleven ‘0’s on the startingpoint.

In the case of the extended CP, the first 12 symbols of the M-SSS may bediscarded, and the remaining symbols may be mapped to the valid OFDMsymbols, which cause to discard only a single symbol among the sequenceof length 61 since eleven ‘0’s are existed on the starting point. Thediscard of the symbol causes the slight degradation of the correlationproperty of other SSS.

The cyclic shift of a sequence and the sequence for different roots mayeasily provide specific cell identifiers up to 504. The reason why theZC sequence is used in the NB-LTE in comparison with the LTE is todecrease the error detection rate. Since a common sequence for twodifferent cell identifier groups is existed, an additional procedure isrequired in the LTE.

Since the M-PSS/M-SSS occur four times within the block of 80 ms, theLTE design of the SSS cannot be used for providing accurate timinginformation within the corresponding block. This is because the specialinterleaving structure that may determine only two positions.Accordingly, a scrambling sequence may be used in an upper part of theZC sequence in order to provide the information of frame timing. Fourscrambling sequences may be required to determine four positions withinthe block of 80 ms, which may influence on acquiring the accuratetiming.

FIG. 22 is a diagram illustrating a method for generating M-SSSaccording to an embodiment of the present invention.

Referring to FIG. 22, the M-SSS may be defined ass_p,q(n)=a_p(n)·b_q(n). Herein, p={0, 1, . . . , 503} represents cellidentifiers and q={0, 1, 2, 3} determines the position of the M-SSS(i.e., the number of M-SSS within the block of 80 ms which is generatedbefore the latest SSS). In addition, a_p(n) and b_q(n) may be determinedby Equations 8 and 9 below.

$\begin{matrix}{\begin{matrix}{{{a_{p}(n)} = 0},\mspace{45mu}{n = {\left\{ {{0 - 4},{66 - 71}} \right\}}}} \\{{= {a_{p}\left( {n - k_{p} - 5} \right)}},\mspace{45mu}{n = {\left\{ {5,6,\ldots\mspace{14mu},65} \right\}}}}\end{matrix}{\quad{{{a_{p}(n)} = e^{- \frac{j\;\pi\;{n{(p)}}{n{({n + 1})}}}{61}}},\mspace{14mu}{n = {\left\{ {0,1,\ldots\mspace{14mu},61} \right\}}}}}} & \left\lbrack {{Equation}\mspace{14mu} 8} \right\rbrack \\{{{{b_{q}(n)} = {{{b\left( {{mod}\left( {{n - l_{q}},63} \right)} \right)}\mspace{45mu} n} = \left\{ {0,1,{\ldots\mspace{14mu} 60}} \right\}}},{q = \left\{ {0,1,2,3} \right\}},{l_{0} = 0},{l_{1} = 3},{l_{2} = 7},{l_{3} = {11}}}{{{b\left( {n + 6} \right)} = {{mod}\left( {{{b(n)} + {b\left( {n + 1} \right)}},2} \right)}},{n = \left\{ {0,1,{\ldots\mspace{14mu} 55}} \right\}},}{{{b(0)} = 1},{{b(m)} = 0},{m = {\left\{ {1,2,3,4,5} \right\}}}}} & \left\lbrack {{Equation}\mspace{14mu} 9} \right\rbrack\end{matrix}$

Referring to Equation 8, a_p(n) is the ZC sequence and determines a cellidentifier group. m(p) and cyclic shift k_p may be used for providing aspecific cell identifier. Referring to Equation 9, b_q(n) may be thescrambling sequence that includes a cyclic shift of the basic sequenceb_(n), and may be used for indicating the position of the M-SSS in theM-frame in order to acquire the frame timing. The cyclic shift l_q maybe determined according to the value q.

The value of m(p) with respect to the specific p may be determined suchas m(p)=1+mod(p, 61), the value of k_p may be determined such ask_p=7[p/61].

FIG. 23 illustrates an example of a method for implementing M-PSS towhich the method proposed in the present disclosure can be applied.

Particularly, FIG. 23 shows a method for generating an M-PSS using acomplementary Golay sequence.

As shown in FIG. 23, using a complementary Golay sequence pair, a CGSthat is going to be transmitted to each OFDM symbol is selected (i.e.,select a(n) or b(n)).

Next, in the case of using a cover code, c(1) to c(N) may be multipliedto each CGS, and in the case of not using the cover code, 1 may beinputted to all of c(n).

Subsequently, the DFT and the IFFT are performed for each symbol, andtransmitted to each OFDM symbol on time domain.

Additionally, the ZC sequence of length 12 may also generate a sequencethat is going to be transmitted to each OFDM symbol.

In this case, by using the same method applied in FIG. 23, the M-PSS maybe implemented.

NB (Narrow Band)-LTE System

Hereinafter, NB-LTE (or NB-IoT) system will be described.

The UL of NB-LTE is based on SC-FDMA, and this is a special case ofSC-FDMA and may flexibly allocate the bandwidth of the UE includingsingle tone transmission.

One important aspect for the UL SC-FDMA is to enable time of a multipleof co-scheduled UEs coincide with each other so that the arrival timedifference in the base station to be within the cyclic prefix (CP).

Ideally, the UL 15 kHz subcarrier spacing should be used in NB-LTE, butthe time-accuracy, which may be achieved when detecting PRACH from theUEs in a very poor coverage condition, should be considered.

Hence, CP duration needs to be increased.

One way to achieve the above purpose is to reduce the subcarrier spacingfor NB-LTE M-PUSCH to 2.5 kHz by dividing 15 kHz subcarrier spacing by6.

Another motive for reducing subcarrier spacing is to allow a usermultiplexing of a high level.

For example, one user is basically allocated to one subcarrier.

This is more effective for UEs in a condition that the coverage is verylimited like UEs having no benefit from allocation of a high bandwidthwhile the capacity increases due to the simultaneous use of the maximumTX power of a multiple of UEs.

SC-FDMA is used for transmission of a multiple of tones in order tosupport a higher data rate along with the additional PAPR reductiontechnology.

The UL NB-LTE includes 3 basic channels including M-PRACH, M-PUCCH andM-PUSCH.

The design of M-PUCCH discuses at least three alternative plans asfollows.

-   -   One tone in each edge of the system bandwidth    -   UL control information transmission on M-PRACH or M-PUSCH    -   Not having dedicated UL control channel

Time-Domain Frame and Structure

In the UL of NB-LTE having 2.5 kHz subcarrier spacing, the wirelessframe and the subframe are defined as 60 ms and 6 ms, respectively.

As in the DL of NB-LTE, M-frame and M-subframe are defined in the samemanner in the UL link of the NB-LTE.

FIG. 24 illustrates how the UL numerology is stretched in the timedomain.

The NB-LTE carrier includes 5 PRBs in the frequency domain. Each NB-LTEPRB includes 12 subcarriers.

The UL frame structure based on 2.5 kHz subcarrier spacing isillustrated in FIG. 17.

FIG. 24 illustrates an example of UL numerology which is stretched inthe time domain when the subcarrier spacing is reduced from 15 kHz to2.5 kHz.

FIG. 25 illustrates an example of time units for the UL of NB-LTE basedon the 2.5 kHz subcarrier spacing.

Operation System of NB-LTE System

FIG. 26 illustrates an example of an operation system of NB-LTE systemto which the method proposed in the present specification is applicable.

Specifically, FIG. 26(a) illustrates an in-band system, FIG. 26(b)illustrates a guard-band system, and FIG. 26(c) illustrates astand-alone system.

The in-band system may be expressed as an in-band mode, the guard-bandsystem may be expressed as a guard-band mode, and the stand-alone systemmay be expressed as a stand-alone mode.

The in-band system of FIG. 26(a) indicates a system or mode which uses aspecific 1 RB within the legacy LTE band for NB-LTE (or LTE-NB) and maybe operated by allocating some resource blocks of the LTE systemcarrier.

The guard-band system of FIG. 26(b) indicates a system or mode whichuses NB-LTE in the space which is reserved for the guard band of thelegacy LTE band and may be operated by allocating the guard-band of LTEcarrier which is not used as the resource block in the LTE system.

The legacy LTE band includes the minimum 100 kHz at the last of each LTEband.

In order to use 200 kHz, 2 non-continuous guardbands may be used.

The in-band system and the guard-band system indicate the structurewhere NB-LTE co-exists within the legacy LTE band.

In contrast, the standalone system of FIG. 26(c) indicates a system ormode which is independently configured from the legacy LTE band and maybe operated by separately allocating the frequency band (futurereallocated GSM carrier) which is used in the GERAN.

FIG. 27 illustrates an example of an NB-frame structure of 15 kHzsubcarrier spacing to which the method proposed in the presentspecification is applicable.

As illustrated in FIG. 27, it may be understood that the NB-framestructure for 15 kHz subcarrier spacing is the same as the framestructure of the legacy system (LTE system).

Namely, 10 ms NB-frame includes 10 1 ms NB-subframes, and 1 msNB-subframe includes 2 0.5 ms NB-slots.

Further, 0.5 ms NB-slot includes 7 OFDM symbols.

FIG. 28 illustrates an example of NB-frame structure for 3.75 kHzsubcarrier spacing to which the method proposed in the presentspecification is applicable.

Referring to FIG. 28, 10 ms NB-frame includes 5 2 ms NB-subframes, and 2ms NB-subframe includes 7 OFDM symbols one guard-period (GP).

The 2 ms NB-subframe may also be expressed as NB-slot or NB-RU (resourceunit), etc.

FIG. 29 illustrates an example of NB subframe structure in 3.75 kHzsubcarrier spacing to which the method proposed in the presentspecification is applicable.

FIG. 29 shows the correspondence between legacy LTE subframe structureand 3.75 subframe structure.

Referring to FIG. 29, subframe (2 ms) of 3.75 kHz corresponds to 2 1 mssubframes (or 1 ms TTIs) of the legacy LTE.

UL Processing Chain

In the NB LTE system, the single tone transmission is used for M-PUSCH(or NPUSCH) in order to minimize PAPR, and as a result, the coverage isimproved.

A specific procedure of the M-PUSCH processing is described withreference to FIG. 30.

FIG. 30 illustrates an example of PUSCH processing in NB-IoT system towhich the method proposed in the present specification is applicable.

FIG. 31 illustrates an example of an LTE turbo encoder used for PUSCH inNB-IoT system to which the method proposed in the present specificationis applicable.

CRC generation of M-PUSCH uses a polynomial which is the same as apolynomial for generating the CRC of M-PDSCH.

In the NB LTE system, the channel coding of the M-PUSCH is based on theLTE turbo code encoder as illustrated in FIG. 31.

The interleaving and the rate matching are the same as the method ofM-PDSCH.

Encoded bits after the rate matching are scrambled with the scramblingmask which is generated according to the RNTI associated with theM-M-PUSCH transmission.

The scrambled codeword is modulated with BPSK or QPSK according to Table6 below.

Table 6 shows an example of BPSK modulation mapping.

TABLE 6 b(i) I Q 0 1 0 1 −1 0

The modulated symbols are grouped in the subcarriers allocated to theM-PUSCH.

In the case of the single tone transmission, the transform precodingblock of FIG. 19 is omitted and the group of MF tones is directed by thebase station. The MF may be 1, 2, 4, or 8.

If only one tone is directed from the base station (i.e., MF=1), the onedirected tone is used for M-PUSCH transmission.

Otherwise, if a multitude of tones are directed from the base station,each set of log 2MF+log 2MQ bits is determined through the tonetransmitted between MF tones and the combination of modulation symbols.

Here, the MQ corresponds the modulation order, and the value is 2 in theBPSK and the value is 4 in the QPSK.

With respect to the SC-FDMA transmission having a multiple of continuoussubcarriers within one cluster, the transform precoding block of FIG. 30is applied to each group in order to obtain frequency-domain symbols(known as SC-FDMA).

In addition, in order to further lower PAPR for BPSK/QPSK, additionallypotential PAPR reduction technologies may be applied.

An example of PAPR reduction technologies is to apply an additionalprecoding filter of M×L dimension (M>L) to the filer of the L×L DFTprecoding.

Thereafter, the first baseband time-continuous signal is generated basedon frequency-domain symbols as in equation 10 below.

$\begin{matrix}{{s_{l}(t)} = {\sum\limits_{k = {{- M}/2}}^{{M/2} - 1}{a_{k,l} \cdot e^{j\; 2\;{\pi{({k + {1/2}})}}\Delta\;{f{({t - {N_{{CP},l}T_{s}}})}}}}}} & \left\lbrack {{Equation}\mspace{14mu} 10} \right\rbrack\end{matrix}$

With respect to 0≤t<(N_(CP,l)+N)×T_(s) of Equation 10, M means thenumber of subcarriers allocated to M-PUSCH, N=128, Δf=2.5 kHz,T_(s)=1/320000 and a_(k,l) means the frequency-domain symbol of thesubcarrier corresponding to k+M/2.

Table 7 below shows values of used N_(CP,l).

In a special case that M=1, the first baseband time-continuous signal isgenerated based on frequency-domain symbols as Equation 10 below.s _(l)(t)=a _(0,l) ·e ^(−jπΔf(t−N) ^(CP,l) ^(T) ^(s) ⁾  [Equation 11]

Table 7 shows an example of CUL CP length.

TABLE 7 Configuration Cyclic prefix length N_(CP, l) Normal cyclicprefix 10 for l = 0 9 for l = 1, 2, . . . , 6

In the above Equations 10 and 11, Δf means a subcarrier spacing andT_(s) means the sampling time.

As described above, the NB-IoT system means a system for supportingcommunication of UEs which use a narrowband and have the characteristicof a low cost and a low complexity.

Further, the NB-IoT system considers an access situation of a multipleof UEs using a restricted communication resource and has the goal ofsupporting a coverage wider than the coverage of the legacy LTE.

In order to obtain the effects of the coverage extension through thelimited number of resources (e.g., subcarrier), the NB-IoT systemconsiders an UL transmission method and repetitive transmission methodwhich uses a single tone or single subcarrier.

However, in the case of NB-IoT system, the simultaneous access to asufficient number of UEs may not be achieved by a multiplexing method inthe existing frequency domain and time domain due to the basicallyrestricted communication resource.

If the case that the UE, which needs data transmission, needs to waitfor the data transmission due to the failure of the data channelallocation therefor, the energy consumption of the UE due to the datatransmission delay may occur.

Such a situation finally results in a significant reduction of theenergy efficiency of NB-IoT system.

Hence, in order to solve the above problem, the present specificationproposes a method for increasing the number of UEs which are multiplexedthrough the same resource (time and/or frequency resource) in the NB-IoT(or NB-LTE) system, solving the problem of the inter-cell interference(ICI) which may be generated between adjacent cells, and extending thecoverage.

Further, the method proposed in the present specification has thefeature of considering the PAPR (peak-to-average power ratio)performance which is one of importance indexes in the NB-IoT.

Hereafter, the description is limited to the PUSCH in the NB-IoT systemfor the convenience of description, but the method proposed in thepresent specification may also be applied to the transmission of a DL/ULdata channel of another system which additionally requires amultiplexing gain and a DL/UL control channel.

The expression “A and/or B” used in the present specification may beunderstood in the same manner as the expression including “at least oneamong A and B”.

Method of Using a Codeword Cover for PUSCH Transmission

First, a method of using a codeword cover for the multiplexing of thePUSCH transmission between UEs in the NB-IoT system is described.

As described above, the NB-IoT system supports repetition of data orsignals through a multiple of symbols in order to support the coverageenhancement.

Hence, the present specification presents a method of increasing amultiplexing gain by applying a codeword cover to several repeated timeunits.

At this time, the time unit, which becomes the criterion of therepetition, may include a radio frame, a subframe bundle or a subframegroup (or set), a subframe, a slot, a symbol, or a symbol group, andvarious time units, which may be considered in the NB-IoT, may be used.

Hereinafter, the description is made on the basis of the repetitionpattern of the symbol unit for the convenience of description. Yet, themethod suggested in the present specification may also be applied to asystem which uses the repetition of other time units in addition to thesymbol unit.

Generally, after a multiple of UEs are allocated the same resource,i.e., the same subcarrier and the same time, from the base station, whenthe UL signal is transmitted to the base station using the allocatedsame resource, it may be impossible to distinguish the received signaldue to a mutual interference.

Hereinafter, when a multiple of UEs transmit an UL signal to the basestation through the same resource using a specific codewords cover, amethod of distinguishing a transmission signal of UEs in the basestation will be specifically described.

FIG. 32 illustrates an example of a method of applying a codeword coverproposed in the present specification to a repeated symbol of a timedomain.

When a specific data is repeated (transmitted) in a specific time unitthrough N symbols, the UE multiplies the (promised) codewords cover oflength N by the N repetition symbols, and then transmits the generatedcodeword covered symbol to the base station.

Here, the codewords, which are used for the codewords cover which areapplied to the N repetition symbols, are previously fixed values or areconfigured by the base station (e.g., eNodeB), and the set informationmay be transmitted by the base station to the UE through a signaling.

The signaling may be a RRC signaling, a physical signaling, and thelike.

FIG. 32 shows a process that the codewords cover of length 4 is appliedto 4 repetition symbols.

Referring to FIG. 32, data having value “1” are repeated through 4symbols, and the codeword cover of length 4 is applied to the 4 repeatedsymbols so that the codeword covered symbol of length 4 is generated.

Configuration of Orthogonal Codewords Cover

Next, a method of configuring an orthogonal codewords cover is describedas a method of configuring a codewords cover which is proposed in thepresent specification.

The orthogonal codewords cover has an advantage that the distinctionbetween UEs having been allocated each codewords cover may become clear.

In the case of a system which is sensitive to PAPR performance likeNB-IoT, the orthogonal codeword cover is preferably configured ordesigned not to damage the PAPR performance.

Further, one of the factors influencing the change of the phase in thecontinuous symbol is a zero crossing generated due to a rapid change ofthe phase between symbols, or a phenomenon similar to (or close to) thezero crossing.

Hence, when the orthogonal codeword cover proposed in the presentspecification is configured, in the symbol set having the orthogonalcodewords cover applied thereto, the phase change between symbols ispreferably generated in the smoothest way possible.

As a way to satisfy such a condition, the present specification providesa method of configuring an orthogonal codewords cover using DFT matrix.

Since each row vector configuring the DFT matrix has an orthogonalproperty between them, it is appropriate to configure an orthogonalcodewords cover proposed in the present specification using the rowvector of the DFT matrix.

Yet, in order to minimize the PAPR effects in the above-described NB-IoTsystem, the method of selecting only a portion from row vectors of theDFT matrix will be additionally described.

For example, (1, −1, 1, −1) corresponding to one row vector of 4×4 DFTmatrix satisfies the orthogonal property which is at right angles toother row vectors, but when multiplied by the symbol repetition set, itmay cause a zero crossing between adjacent symbols, and thus it isdesirable to be exempted at the time of determining the orthogonalcodewords cover.

Further, row vectors of some DFT matrixes do not generate a zerocrossing but may generate effects similar to (or close to) the zerocrossing.

Hence, the method proposed in the present specification sequentiallyselects or determines the codewords cover by putting priority on thevectors which do not increase the PAPR of NB-IoT system in the processof generating or configuring an orthogonal codewords cover using DFTmatrix.

Namely, when the orthogonal codewords cover is configured using theabove-described DFT matrix, the codewords covers with less increasingeffects of the PAPR are first defined to be selected.

The method of selecting an orthogonal codewords cover using the DFTmatrix may be specifically expressed as shown in Equation 12 below.

Equation 12 below shows a method of generating DFT matrix (WN) of sizeN.

$\begin{matrix}{W_{N} = {e^{{- j}\; 2{\pi/N}} = {{\cos\left( \frac{2\pi}{N} \right)} - {j \cdot {\sin\left( \frac{2\pi}{N} \right)}}}}} & \left\lbrack {{Equation}\mspace{14mu} 12} \right\rbrack\end{matrix}$

The kth row of DFT matrix of size N×N and the element of the nth columnmay be expressed as Equation 13.W _(N)(k,n)=(W _(N))^(k·n)  [Equation 13]

Namely, when the DFT matrix is configured using Equations 12 and 13, itis desirable to select the row vector of the DFT matrix close to “0” or“N” as value k.

It is because when value k is close to “0” or “N”, the influence of thephase change influencing between respective symbols of the originalsignal becomes small.

In contrast, as value k is close to N/2, the influence of the phasechange influencing between respective symbols of the original signal bythe row vector of DFT matrix increases.

Hence, when the orthogonal codewords cover is selected using the DFTmatrix proposed in the present specification, value k indicting the rowvector index of the DFT matrix is defined to be selected from a value ofwhich the absolute value (k−N/2)(abs(k−N/2)) is the largest.

For example, when the codewords cover having 16 bit length isconfigured, if 6 codewords covers are selected among 16 availablecodewords covers and used, the row vector index of the DFT matrixcorresponding to the selected codewords cover may be determined as {0,15, 1, 14, 2 and 13}.

Further, when each codewords cover corresponding to the row vector indexof the DFT matrix is allocated to the UEs, the base station may allocatethe codewords cover suitable to each UE in consideration of the currentsituation of each UE and the capability of each UE.

In this case, in each UE, the priority order of the codewords covers maybe determined on the basis of various informations such as theimportance of data, the currently remaining power situation, coverageclass information, CQI, etc.

In this case, each UE is sequentially allocated from the codewords coverwith the least influence of PAPR according to the priority order of thecodewords covers.

Likewise, with respect to the information related to the priority orderof the codewords cover, the UE may directly provide the information tothe base station through PUSCH, PUCCH, or RRC signaling. Alternatively,the base station may assume information related to the priority order ofthe codewords cover based on the DM-RS, etc. directly transmitted by theUE.

Configuration of Codewords Cover in Consideration of Inter-CellInterference (ICI)

When UEs located at the adjacent cell use the same codewords cover,inter-cell interference may occur.

In particular, in the case of extreme coverage UEs located at the celledge, if an adjacent UE uses the same codewords cover, the influence ofthe interference reaching the cell of the extreme coverage UE becomesvery significant.

Hence, hereinafter, a method of configuring a codewords cover forminimizing the inter-cell interference problem will be specificallydescribed.

The extreme coverage UE used in the present specification is a UElocated at the cell edge and may be expressed as a first UE, and anormal coverage UE is a UE located at the center of the cell or near thecenter of the cell and may be expressed as a second UE.

Inter-Cell Interference Coordination Using Codewords Cover

The influence of the inter-cell interference is significantly generatedgenerally by UE(s) located at the cell edge, in other words, by theextreme coverage UE(s).

Here, the extreme coverage UE means a UE located at the cell coverage,and the normal coverage UE means a UE located at the center of the cellor near the center of the cell.

In contrast, the UEs located at the normal coverage which is not at thecell edge give relatively less influence of the inter-cell interference.

Hence, hereinafter, the method of allocating the codewords coveraccording to the coverage class differently by UEs in order to avoid theinfluence of the ICI will be described.

The coverage class may mean a class corresponding to the area(s) whichare generated by classifying the area (or range) covered by the cellaccording to a certain standard.

Hence, the number of the coverage classes may be determined as thenumber of the classified area(s).

A UE located in a normal coverage (or a UE located in an areacorresponding to a normal coverage class) may be expressed as a normalcoverage UE, and an UE located in an extreme coverage may be expressedas an extreme coverage UE.

Specifically, normal coverage UEs may use an available codewords coverin order to enhance a multiplexing gain.

At this time, the base station may distinguish signals transmitted fromthe UE through the same frequency (or subcarrier) and the same time,i.e., through the same resource.

Further, the codewords cover used by normal coverage (class) UEs may beused in all cells in the same manner.

Hence, in this case, it is possible to configure the codewords cover ina manner that maximizes the multiplexing gain which may be utilized ineach cell by enhancing the reuse factor of the codewords cover.

In contrast, the codewords cover allocated to UEs located in the extremecoverage, i.e., the extreme coverage UEs may be configured not to bereused in the adjacent cell.

As such, even if the transmission signal of the extreme coverage UEsinterferes with the adjacent cell, the base station may distinguish thesignal received from the UEs through the codewords cover.

FIG. 33 illustrates an example of a method of using different orthogonalcodes depending on the coverage class proposed in the presentspecification.

Namely, FIG. 33 shows an example of extreme coverage UEs 3310 and 3320using different codewords covers 3310-1 and 3320-2 between cells.

Here, the criteria for distinguishing or defining the coverage class inorder to differentially use the codewords cover (by UEs) may bevariously configured.

For example, the coverage class may be defined or configured based onthe distance between the UE and the base station and the size of thereceiving power (of the UE) in the base station.

Namely, when the receiving power of the UE is equal to or greater than acertain threshold, the corresponding coverage class is defined as anormal coverage class, and the base station may reuse the codewordscover between cells so as to be allocated to the UE.

Further, when the receiving power of the UE is equal to or less than acertain threshold, the corresponding coverage class is defined as theextreme coverage class, and the base station allocates the cell-specificcodewords to each UE.

Further, the criterion of the coverage class may be set as the size ofthe interference influencing the adjacent cell.

Namely, when the influence of a specific UE to the adjacent cell isequal to or less than a certain threshold, the specific UE is defined asa normal coverage UE, and when the influence of a specific UE to theadjacent cell is equal to or greater than a certain threshold, thespecific UE may be defined as an extreme coverage UE.

Likewise, the criterion for determining the coverage class may assumethe coverage class value of each UE using the UL reference signal whichthe base station receives from the UE.

Further, the coverage class may be a predetermined fixed value or may beconfigured by the base station, and the base station may transmit thecoverage class to the UE through a signaling.

Here, when the base station configures the coverage class, the basestation directly informs the UE of the coverage class and may enable theUE to selectively determine the codewords cover.

Further, the base station may directly configure the codewords coverused by the UE instead of the coverage class information and transmitthe corresponding codewords cover index to the UE through a signaling.

Here, the coverage class information and the codewords cover index mayhave been mapped in advance.

Frequency Hopping Method

Hereinafter, as a way to resolve an inter-cell interference which mayoccur when the UEs proposed in the present specification use the samecodewords cover, a method of distinguishing a cell using a frequencyhopping pattern will be described.

With respect to the frequency hopping method proposed in the presentspecification, all cells may share and use all codewords covers usablein the codewords cover length or repetition length of each UE.

Further, the frequency hopping method proposed in the presentspecification distinguish the UE allocated to each cell by applying thepattern of the frequency hopping for obtaining the frequency diversitydifferently per cell.

Here, the codewords cover allocated to each cell may be distinguishedthrough the frequency hopping pattern, and thus the codewords covervectors of each cell may be fully reused.

Further, the frequency hopping pattern may be set in the symbol groupunit (e.g., slot unit, subframe unit, group unit of subframes) includingthe symbol unit or a plurality of symbols.

If the system to which the above-described frequency hopping pattern isapplied supports the frequency hopping method of several units, the basestation may inform the UE of the unit of the frequency hopping pattern(or the unit of the hopping mode) that is used, through an RRCsignaling, etc.

The selection of the frequency hopping pattern and/or codewords coverallocated to each UE is configured by the base station, the configuredfrequency hopping pattern and/or codewords cover may be indicated to theUE through a signaling.

Further, the base station allocates the codewords cover fitting thecoverage class of each UE and determines the frequency hopping patternaccording thereto.

At this time, the base station already knows all UEs accessed to thecell of the base station and the frequency hopping pattern of theadjacent cell, and thus the optimized resource distribution becomespossible.

Further, each UE may dynamically configure the frequency hopping patternand the codewords cover using the predefined (or pre-promised) functionusing cell I, UE IE (e.g., RNTI) or coverage class information.

Such a method of configuring the dynamic frequency hopping pattern andthe codewords cover has an advantage of being able to reduce thesignaling overhead in that a signaling does not need to be transmittedseparately in order to indicate the frequency hopping pattern and thecodewords cover to the UE.

At this time, the UE may determine both the frequency hopping patternand the codewords cover for itself, and it is possible that only one ofthe two is determined for itself and the other may be obtained throughthe signaling of the base station.

Additionally, the above-described frequency hopping method may not beapplicable depending on the situation.

To this end, the base station may inform the UE of the frequency hoppingenable or frequency hopping disable information indicating whether thefrequency hopping is possible, through a signaling.

The signaling may be an RRC signaling.

The UE having received a signaling indicating whether the frequencyhopping is possible recognizes whether the frequency hopping isapplicable through the received signaling, and the UE may (promptly)apply or not apply the frequency hopping according thereto.

Alternatively, the UE first recognizes whether the frequency hopping issupportable through the RRC signaling received from the base station,then the UE may obtain the parameter for the accurate frequency hoppingthrough the DCI (DL Control Information) received from the base stationand perform the following operation.

Alternatively, the base station may transmit the DCI information to theUE once more so that the frequency hopping is not supported.

Further, the base station may update the information related to thefrequency hopping by additionally transmitting DCI information to theUE.

The purpose thereof may be to adjust the frequency hopping parameteraccurately in order to more efficiently use the frequency resource ormore effectively manage the inter-cell interference.

Further, when the capabilities for the frequency hopping between UEs aredifferent, each UE may be configured to report the UE's capabilityrelated to the frequency hopping to the base station through the ULsignaling.

In this case, the UL signaling reported by the UE may be transmitted inthe form of message 1 (random access preamble) or message 3 (scheduledtransmission) which is used in the random access process.

The base station may determine whether to use the frequency hopping ofthe UE based on the reporting of the UE and inform the UE of thedetermination.

FIG. 34 illustrates an example of a method of multiplexing an UL systemof a user equipment (UE) by using a codeword cover and a frequencyhopping pattern which are proposed in the present specification.

FIG. 35 is a flowchart showing an example of a method of multiplexing anUL signal between user equipments, which is proposed in the presentspecification.

Referring to FIG. 35, the UE receives control information related to thecodewords cover used for the multiplexing of a multiple of UEs from thebase station (S3510).

The codewords cover may have a mapping relation with the coverage class.

The coverage class may be determined using at least one of the distancebetween the UE and the base station, the size of the receiving power inthe base station, and the size of the interference influencing theadjacent cell.

Further, the control information may further include at least one of thefrequency hopping information indicating the frequency hopping patternrelated to the transmission of the UL signal and the informationindicating whether the frequency hopping is used.

Further, the frequency hopping pattern may be set differently per cell.

The control information may be received from the base station throughthe RRC (radio resource control) signal or DCI (DL control information).

Thereafter, the UE generates the transmission symbol of a specificlength by repeating the data symbol in a specific time unit (S3520).

The specific time unit may be a symbol unit, a symbol group unit, a slotunit, a subframe unit, a subframe group unit, or a wireless frame unit.

Thereafter, the UE generates the UL link signal by applying a codewordscover of the specific length to the generated transmission symbol(S3530).

The codewords cover of the specific length may be an orthogonalcodewords cover which is generated using the DFT (discrete Fouriertransform) matrix.

The codewords cover of the specific length may be an orthogonalcodewords cover corresponding to a specific row vector of the DFTmatrix.

The row vector of the DFT matrix has the index of from 0 to a value at aspecific length−1, and the specific row vector may be a row vectorcorresponding to the index close to “0” or the value of the specificlength.

Thereafter, the UE transmits the generated UL link signal to the basestation through the single tone (S3540).

Device to which the Present Invention is Applicable

FIG. 36 illustrates an example of an internal block diagram of awireless communication device to which the methods proposed in thepresent specification are applicable.

Referring to FIG. 36, a wireless communication system includes a basestation 3610 and a multiple of UEs 3620 located within the area of thebase station 3610.

The base station 3610 includes a processor 3611, a memory 2612, and anRF (radio frequency) unit 3613. The processor 3611 implements thefunction, process and/or method proposed in FIGS. 1 to 35. The layers ofthe wireless interface protocol may be implemented by the processor3611. The memory 3612 is connected to the processor 3611 and storesvarious informations for operating the processor 3611. The RF unit 3613is connected to the processor 3611 and transmits and/or receives awireless signal.

The UE 3620 includes a processor 3621, a memory 3622, and an RF unit3623. The processor 3621 implements the function, process and/or methodproposed in FIGS. 1 to 35. The layers of the wireless interface protocolmay be implemented by the processor 3621. The memory 3622 is connectedto the processor 3621 and stores various informations for operating theprocessor 3621. The RF unit 3623 is connected to the processor 3621 andtransmits and/or receives a wireless signal.

The memories 3612 and 3622 may be inside or outside the processors 3611and 3621 and may be connected to the processors 3611 and 3621 bywell-known various means.

Further, the base station and/or the UE 3620 may have a single antennaor a multiple antenna.

According to the embodiments of the present invention, a multiplexingbetween UEs may be supported by using an orthogonal codeword cover whichuses DFT matrix.

According to the embodiments of the present invention, an inter-cellinterference may be prevented by allocating a codeword cover to a UE inconsideration of a coverage class.

A method for transmitting an UL signal in an UL communication system ofthe present specification was described centering on the example ofbeing applied to 3GPP LTE/LTE-A, but it is possible to be applied tovarious wireless communication systems such as 5G system as well as 3GPPLTE/LTE-A system.

The above-described embodiments are combinations of components andfeatures of the present invention in a prescribed form. Each componentor feature should be considered selective unless separately mentioneddifferently. Each component or feature may be executed in a form that isnot combined with other components or features. Further, it is possibleto configure the embodiment of the present invention by combining somecomponents and/or features. The order of operations described in theembodiments of the present invention may be changed. Some components orfeatures of a certain embodiment may be included in another embodimentor may be substituted with the corresponding components or features ofanother embodiment. It is obvious that an embodiment may be configuredby combining claims which are not directly cited, or a new claim may beadded by amendment.

The embodiments according to the present invention may be implemented byhardware, firmware, software, or a combination thereof. In the case ofimplementation by hardware, one embodiment of the present invention maybe implemented by one or more of ASICs (application specific integratedcircuits), DSPs (digital signal processors), DSPDs (digital signalprocessing devices), PLDs (programmable logic devices), FPGAs (fieldprogrammable gate arrays), processors, controls, microcontrollers,microprocessors, and the like.

In the case of implementation by firmware or software, one embodiment ofthe present invention may be implemented in the form of a module,procedure, function and the like for performing the functions oroperations described above. The software code may be stored in thememory so as to be operated by the processor. The memory may be locatedinside or outside the processor, and thus the memory maytransmit/received to/from the processor.

It is obvious to one of ordinary skill in the art that the presentinvention may be embodied into another specific form within the scope ofthe essential features of the present invention. Hence, the abovedetailed description of the invention should not be understood aslimitative and should be understood as illustrative. The scope of thepresent invention should be determined by a reasonable analysis of theattached claims, and all the changes within the equivalent range of thepresent invention are included in the scope of the present invention.

What is claimed is:
 1. A method of transmitting an uplink (UL) signal ina wireless communication system, the method performed by a userequipment (UE) and comprising: receiving control information from a basestation (BS), the control information related to a codeword cover usedfor a multiplexing multiple UEs; generating a transmission symbol byrepeating a data symbol in a specific time unit; generating the ULsignal by applying the codeword cover to the generated transmissionsymbol; and transmitting the generated UL signal to the BS through asingle tone, wherein the codeword cover is an orthogonal codeword covercorresponding to a specific row vector of a discrete Fourier transform(DFT) matrix, wherein the specific row vector has indexes of from 0 to{(value of a specific length)−1}, and wherein the specific row vectorcorresponds to an index close to the value of the specific length or 0.2. The method of claim 1, wherein the specific time unit is a symbolunit, a symbol group unit, a slot unit, a subframe unit, a subframegroup unit, or a wireless frame unit.
 3. The method of claim 1, wherein:the codeword cover has a mapping relation with a coverage class; and thecoverage class corresponds to one or more areas generated by classifyinga range covered by a cell.
 4. The method of claim 3, wherein thecoverage class is determined using at least a distance between the UEand the BS, a size of a receiving power of the BS, or a size of aninterference influencing an adjacent cell.
 5. The method of claim 1,wherein the control information comprises at least frequency hoppinginformation indicating a frequency hopping pattern related totransmission of the UL signal or information indicating whetherfrequency hopping is used.
 6. The method of claim 5, wherein thefrequency hopping pattern is configured differently per cell.
 7. Themethod of claim 1, wherein the control information is received throughRadio Resource Control signaling or Downlink Control Information.
 8. Auser equipment (UE) for transmitting an uplink signal in a wirelesscommunication, the UE comprising: a radio frequency (RF) unit fortransmitting and receiving a wireless signal; and a processorfunctionally connected to the RF unit for: controlling the RF unit toreceive control information from a base station (BS), the controlinformation related to a codeword cover used for multiplexing multipleUEs; generating a transmission symbol by repeating a data symbol in aspecific time unit; generate the UL signal by applying the codewordcover to the generated transmission symbol; and controlling the RF unitto transmit the generated uplink signal to the BS through a single tone,wherein the codeword cover is an orthogonal codeword cover correspondingto a specific row vector of a discrete Fourier transform (DFT) matrix,wherein the specific row vector has indexes of from 0 to {(value of aspecific length)−1}, and wherein the specific row vector corresponds toan index close to the value of the specific length or
 0. 9. The UE ofclaim 8, wherein the specific time unit is a symbol unit, a symbol groupunit, a slot unit, a subframe unit, a subframe group unit, or a wirelessframe unit.
 10. The UE of claim 8, wherein: the codeword cover has amapping relation with a coverage class; and the coverage classcorresponds to one or more areas generated by classifying a rangecovered by a cell.
 11. The UE of claim 10, wherein the coverage class isdetermined using at least a distance between the UE and the BS, a sizeof a receiving power of the BS, or a size of an interference influencingan adjacent cell.
 12. The UE of claim 8, wherein the control informationcomprises at least frequency hopping information indicating a frequencyhopping pattern related to transmission of the UL signal or informationindicating whether frequency hopping is used.
 13. The UE of claim 12,wherein the frequency hopping pattern is configured differently percell.
 14. The UE of claim 8, wherein the control information is receivedthrough Radio Resource Control signaling or Downlink ControlInformation.